// SPDX-License-Identifier: GPL-2.0

  /*
   * trace_events_hist - trace event hist triggers
   *

   * Copyright (C) 2015 Tom Zanussi <tom.zanussi@linux.intel.com>
   */
  
  #include <linux/module.h>
  #include <linux/kallsyms.h>

  #include <linux/security.h>

  #include <linux/mutex.h>
  #include <linux/slab.h>
  #include <linux/stacktrace.h>

  #include <linux/rculist.h>

  #include <linux/tracefs.h>

  /* for gfp flag names */
  #include <linux/trace_events.h>
  #include <trace/events/mmflags.h>

  #include "tracing_map.h"

  #include "trace_synth.h"

  #define ERRORS								\
  	C(NONE,			"No error"),				\
  	C(DUPLICATE_VAR,	"Variable already defined"),		\
  	C(VAR_NOT_UNIQUE,	"Variable name not unique, need to use fully qualified name (subsys.event.var) for variable"), \
  	C(TOO_MANY_VARS,	"Too many variables defined"),		\
  	C(MALFORMED_ASSIGNMENT,	"Malformed assignment"),		\
  	C(NAMED_MISMATCH,	"Named hist trigger doesn't match existing named trigger (includes variables)"), \
  	C(TRIGGER_EEXIST,	"Hist trigger already exists"),		\
  	C(TRIGGER_ENOENT_CLEAR,	"Can't clear or continue a nonexistent hist trigger"), \
  	C(SET_CLOCK_FAIL,	"Couldn't set trace_clock"),		\
  	C(BAD_FIELD_MODIFIER,	"Invalid field modifier"),		\
  	C(TOO_MANY_SUBEXPR,	"Too many subexpressions (3 max)"),	\
  	C(TIMESTAMP_MISMATCH,	"Timestamp units in expression don't match"), \
  	C(TOO_MANY_FIELD_VARS,	"Too many field variables defined"),	\
  	C(EVENT_FILE_NOT_FOUND,	"Event file not found"),		\
  	C(HIST_NOT_FOUND,	"Matching event histogram not found"),	\
  	C(HIST_CREATE_FAIL,	"Couldn't create histogram for field"),	\
  	C(SYNTH_VAR_NOT_FOUND,	"Couldn't find synthetic variable"),	\
  	C(SYNTH_EVENT_NOT_FOUND,"Couldn't find synthetic event"),	\
  	C(SYNTH_TYPE_MISMATCH,	"Param type doesn't match synthetic event field type"), \
  	C(SYNTH_COUNT_MISMATCH,	"Param count doesn't match synthetic event field count"), \
  	C(FIELD_VAR_PARSE_FAIL,	"Couldn't parse field variable"),	\
  	C(VAR_CREATE_FIND_FAIL,	"Couldn't create or find variable"),	\
  	C(ONX_NOT_VAR,		"For onmax(x) or onchange(x), x must be a variable"), \
  	C(ONX_VAR_NOT_FOUND,	"Couldn't find onmax or onchange variable"), \
  	C(ONX_VAR_CREATE_FAIL,	"Couldn't create onmax or onchange variable"), \
  	C(FIELD_VAR_CREATE_FAIL,"Couldn't create field variable"),	\
  	C(TOO_MANY_PARAMS,	"Too many action params"),		\
  	C(PARAM_NOT_FOUND,	"Couldn't find param"),			\
  	C(INVALID_PARAM,	"Invalid action param"),		\
  	C(ACTION_NOT_FOUND,	"No action found"),			\
  	C(NO_SAVE_PARAMS,	"No params found for save()"),		\
  	C(TOO_MANY_SAVE_ACTIONS,"Can't have more than one save() action per hist"), \
  	C(ACTION_MISMATCH,	"Handler doesn't support action"),	\
  	C(NO_CLOSING_PAREN,	"No closing paren found"),		\
  	C(SUBSYS_NOT_FOUND,	"Missing subsystem"),			\
  	C(INVALID_SUBSYS_EVENT,	"Invalid subsystem or event name"),	\

  	C(INVALID_REF_KEY,	"Using variable references in keys not supported"), \

  	C(VAR_NOT_FOUND,	"Couldn't find variable"),		\

  	C(FIELD_NOT_FOUND,	"Couldn't find field"),			\
  	C(EMPTY_ASSIGNMENT,	"Empty assignment"),			\
  	C(INVALID_SORT_MODIFIER,"Invalid sort modifier"),		\
  	C(EMPTY_SORT_FIELD,	"Empty sort field"),			\
  	C(TOO_MANY_SORT_FIELDS,	"Too many sort fields (Max = 2)"),	\
  	C(INVALID_SORT_FIELD,	"Sort field must be a key or a val"),

  
  #undef C
  #define C(a, b)		HIST_ERR_##a
  
  enum { ERRORS };
  
  #undef C
  #define C(a, b)		b
  
  static const char *err_text[] = { ERRORS };

  struct hist_field;

  typedef u64 (*hist_field_fn_t) (struct hist_field *field,
  				struct tracing_map_elt *elt,
  				struct ring_buffer_event *rbe,
  				void *event);

  #define HIST_FIELD_OPERANDS_MAX	2

  #define HIST_FIELDS_MAX		(TRACING_MAP_FIELDS_MAX + TRACING_MAP_VARS_MAX)

  #define HIST_ACTIONS_MAX	8

  enum field_op_id {
  	FIELD_OP_NONE,
  	FIELD_OP_PLUS,
  	FIELD_OP_MINUS,
  	FIELD_OP_UNARY_MINUS,
  };

  /*
   * A hist_var (histogram variable) contains variable information for
   * hist_fields having the HIST_FIELD_FL_VAR or HIST_FIELD_FL_VAR_REF
   * flag set.  A hist_var has a variable name e.g. ts0, and is
   * associated with a given histogram trigger, as specified by
   * hist_data.  The hist_var idx is the unique index assigned to the
   * variable by the hist trigger's tracing_map.  The idx is what is
   * used to set a variable's value and, by a variable reference, to
   * retrieve it.
   */

  struct hist_var {
  	char				*name;
  	struct hist_trigger_data	*hist_data;
  	unsigned int			idx;
  };

  struct hist_field {
  	struct ftrace_event_field	*field;
  	unsigned long			flags;
  	hist_field_fn_t			fn;

  	unsigned int			ref;

  	unsigned int			size;

  	unsigned int			offset;

  	unsigned int                    is_signed;

  	const char			*type;

  	struct hist_field		*operands[HIST_FIELD_OPERANDS_MAX];

  	struct hist_trigger_data	*hist_data;

  
  	/*
  	 * Variable fields contain variable-specific info in var.
  	 */

  	struct hist_var			var;

  	enum field_op_id		operator;

  	char				*system;
  	char				*event_name;

  
  	/*
  	 * The name field is used for EXPR and VAR_REF fields.  VAR
  	 * fields contain the variable name in var.name.
  	 */

  	char				*name;

  
  	/*
  	 * When a histogram trigger is hit, if it has any references
  	 * to variables, the values of those variables are collected
  	 * into a var_ref_vals array by resolve_var_refs().  The
  	 * current value of each variable is read from the tracing_map
  	 * using the hist field's hist_var.idx and entered into the
  	 * var_ref_idx entry i.e. var_ref_vals[var_ref_idx].
  	 */

  	unsigned int			var_ref_idx;
  	bool                            read_once;

  
  	unsigned int			var_str_idx;

  };

  static u64 hist_field_none(struct hist_field *field,
  			   struct tracing_map_elt *elt,
  			   struct ring_buffer_event *rbe,
  			   void *event)

  {
  	return 0;
  }

  static u64 hist_field_counter(struct hist_field *field,
  			      struct tracing_map_elt *elt,
  			      struct ring_buffer_event *rbe,
  			      void *event)

  {
  	return 1;
  }

  static u64 hist_field_string(struct hist_field *hist_field,
  			     struct tracing_map_elt *elt,
  			     struct ring_buffer_event *rbe,
  			     void *event)

  {
  	char *addr = (char *)(event + hist_field->field->offset);
  
  	return (u64)(unsigned long)addr;
  }

  static u64 hist_field_dynstring(struct hist_field *hist_field,
  				struct tracing_map_elt *elt,
  				struct ring_buffer_event *rbe,
  				void *event)

  {
  	u32 str_item = *(u32 *)(event + hist_field->field->offset);
  	int str_loc = str_item & 0xffff;
  	char *addr = (char *)(event + str_loc);
  
  	return (u64)(unsigned long)addr;
  }

  static u64 hist_field_pstring(struct hist_field *hist_field,
  			      struct tracing_map_elt *elt,
  			      struct ring_buffer_event *rbe,
  			      void *event)

  {
  	char **addr = (char **)(event + hist_field->field->offset);
  
  	return (u64)(unsigned long)*addr;
  }

  static u64 hist_field_log2(struct hist_field *hist_field,
  			   struct tracing_map_elt *elt,
  			   struct ring_buffer_event *rbe,
  			   void *event)

  {

  	struct hist_field *operand = hist_field->operands[0];

  	u64 val = operand->fn(operand, elt, rbe, event);

  
  	return (u64) ilog2(roundup_pow_of_two(val));
  }

  static u64 hist_field_plus(struct hist_field *hist_field,
  			   struct tracing_map_elt *elt,
  			   struct ring_buffer_event *rbe,
  			   void *event)

  {
  	struct hist_field *operand1 = hist_field->operands[0];
  	struct hist_field *operand2 = hist_field->operands[1];

  	u64 val1 = operand1->fn(operand1, elt, rbe, event);
  	u64 val2 = operand2->fn(operand2, elt, rbe, event);

  
  	return val1 + val2;
  }

  static u64 hist_field_minus(struct hist_field *hist_field,
  			    struct tracing_map_elt *elt,
  			    struct ring_buffer_event *rbe,
  			    void *event)

  {
  	struct hist_field *operand1 = hist_field->operands[0];
  	struct hist_field *operand2 = hist_field->operands[1];

  	u64 val1 = operand1->fn(operand1, elt, rbe, event);
  	u64 val2 = operand2->fn(operand2, elt, rbe, event);

  
  	return val1 - val2;
  }

  static u64 hist_field_unary_minus(struct hist_field *hist_field,
  				  struct tracing_map_elt *elt,
  				  struct ring_buffer_event *rbe,
  				  void *event)

  {
  	struct hist_field *operand = hist_field->operands[0];

  	s64 sval = (s64)operand->fn(operand, elt, rbe, event);

  	u64 val = (u64)-sval;
  
  	return val;
  }

  #define DEFINE_HIST_FIELD_FN(type)					\

  	static u64 hist_field_##type(struct hist_field *hist_field,	\

  				     struct tracing_map_elt *elt,	\
  				     struct ring_buffer_event *rbe,	\
  				     void *event)			\

  {									\
  	type *addr = (type *)(event + hist_field->field->offset);	\
  									\

  	return (u64)(unsigned long)*addr;				\

  }
  
  DEFINE_HIST_FIELD_FN(s64);
  DEFINE_HIST_FIELD_FN(u64);
  DEFINE_HIST_FIELD_FN(s32);
  DEFINE_HIST_FIELD_FN(u32);
  DEFINE_HIST_FIELD_FN(s16);
  DEFINE_HIST_FIELD_FN(u16);
  DEFINE_HIST_FIELD_FN(s8);
  DEFINE_HIST_FIELD_FN(u8);
  
  #define for_each_hist_field(i, hist_data)	\
  	for ((i) = 0; (i) < (hist_data)->n_fields; (i)++)
  
  #define for_each_hist_val_field(i, hist_data)	\
  	for ((i) = 0; (i) < (hist_data)->n_vals; (i)++)
  
  #define for_each_hist_key_field(i, hist_data)	\
  	for ((i) = (hist_data)->n_vals; (i) < (hist_data)->n_fields; (i)++)

  #define HIST_STACKTRACE_DEPTH	16
  #define HIST_STACKTRACE_SIZE	(HIST_STACKTRACE_DEPTH * sizeof(unsigned long))
  #define HIST_STACKTRACE_SKIP	5

  #define HITCOUNT_IDX		0

  #define HIST_KEY_SIZE_MAX	(MAX_FILTER_STR_VAL + HIST_STACKTRACE_SIZE)

  
  enum hist_field_flags {

  	HIST_FIELD_FL_HITCOUNT		= 1 << 0,
  	HIST_FIELD_FL_KEY		= 1 << 1,
  	HIST_FIELD_FL_STRING		= 1 << 2,
  	HIST_FIELD_FL_HEX		= 1 << 3,
  	HIST_FIELD_FL_SYM		= 1 << 4,
  	HIST_FIELD_FL_SYM_OFFSET	= 1 << 5,
  	HIST_FIELD_FL_EXECNAME		= 1 << 6,
  	HIST_FIELD_FL_SYSCALL		= 1 << 7,
  	HIST_FIELD_FL_STACKTRACE	= 1 << 8,
  	HIST_FIELD_FL_LOG2		= 1 << 9,

  	HIST_FIELD_FL_TIMESTAMP		= 1 << 10,

  	HIST_FIELD_FL_TIMESTAMP_USECS	= 1 << 11,

  	HIST_FIELD_FL_VAR		= 1 << 12,

  	HIST_FIELD_FL_EXPR		= 1 << 13,

  	HIST_FIELD_FL_VAR_REF		= 1 << 14,

  	HIST_FIELD_FL_CPU		= 1 << 15,

  	HIST_FIELD_FL_ALIAS		= 1 << 16,

  };
  
  struct var_defs {
  	unsigned int	n_vars;
  	char		*name[TRACING_MAP_VARS_MAX];
  	char		*expr[TRACING_MAP_VARS_MAX];

  };
  
  struct hist_trigger_attrs {
  	char		*keys_str;

  	char		*vals_str;

  	char		*sort_key_str;

  	char		*name;

  	char		*clock;

  	bool		pause;
  	bool		cont;

  	bool		clear;

  	bool		ts_in_usecs;

  	unsigned int	map_bits;

  
  	char		*assignment_str[TRACING_MAP_VARS_MAX];
  	unsigned int	n_assignments;

  	char		*action_str[HIST_ACTIONS_MAX];
  	unsigned int	n_actions;

  	struct var_defs	var_defs;

  };

  struct field_var {
  	struct hist_field	*var;
  	struct hist_field	*val;
  };
  
  struct field_var_hist {
  	struct hist_trigger_data	*hist_data;
  	char				*cmd;
  };

  struct hist_trigger_data {

  	struct hist_field               *fields[HIST_FIELDS_MAX];

  	unsigned int			n_vals;
  	unsigned int			n_keys;
  	unsigned int			n_fields;

  	unsigned int			n_vars;

  	unsigned int			n_var_str;

  	unsigned int			key_size;
  	struct tracing_map_sort_key	sort_keys[TRACING_MAP_SORT_KEYS_MAX];
  	unsigned int			n_sort_keys;
  	struct trace_event_file		*event_file;
  	struct hist_trigger_attrs	*attrs;
  	struct tracing_map		*map;

  	bool				enable_timestamps;

  	bool				remove;

  	struct hist_field               *var_refs[TRACING_MAP_VARS_MAX];
  	unsigned int			n_var_refs;

  
  	struct action_data		*actions[HIST_ACTIONS_MAX];
  	unsigned int			n_actions;

  
  	struct field_var		*field_vars[SYNTH_FIELDS_MAX];
  	unsigned int			n_field_vars;
  	unsigned int			n_field_var_str;
  	struct field_var_hist		*field_var_hists[SYNTH_FIELDS_MAX];
  	unsigned int			n_field_var_hists;

  	struct field_var		*save_vars[SYNTH_FIELDS_MAX];
  	unsigned int			n_save_vars;
  	unsigned int			n_save_var_str;

  };
  
  struct action_data;
  
  typedef void (*action_fn_t) (struct hist_trigger_data *hist_data,
  			     struct tracing_map_elt *elt, void *rec,

  			     struct ring_buffer_event *rbe, void *key,

  			     struct action_data *data, u64 *var_ref_vals);

  typedef bool (*check_track_val_fn_t) (u64 track_val, u64 var_val);

  enum handler_id {
  	HANDLER_ONMATCH = 1,
  	HANDLER_ONMAX,

  	HANDLER_ONCHANGE,

  };
  
  enum action_id {
  	ACTION_SAVE = 1,
  	ACTION_TRACE,

  	ACTION_SNAPSHOT,

  };

  struct action_data {

  	enum handler_id		handler;
  	enum action_id		action;
  	char			*action_name;

  	action_fn_t		fn;

  	unsigned int		n_params;
  	char			*params[SYNTH_FIELDS_MAX];

  	/*
  	 * When a histogram trigger is hit, the values of any
  	 * references to variables, including variables being passed
  	 * as parameters to synthetic events, are collected into a

  	 * var_ref_vals array.  This var_ref_idx array is an array of
  	 * indices into the var_ref_vals array, one for each synthetic
  	 * event param, and is passed to the synthetic event
  	 * invocation.

  	 */

  	unsigned int		var_ref_idx[TRACING_MAP_VARS_MAX];

  	struct synth_event	*synth_event;

  	bool			use_trace_keyword;
  	char			*synth_event_name;

  	union {
  		struct {

  			char			*event;

  			char			*event_system;
  		} match_data;

  		struct {
  			/*
  			 * var_str contains the $-unstripped variable
  			 * name referenced by var_ref, and used when
  			 * printing the action.  Because var_ref
  			 * creation is deferred to create_actions(),
  			 * we need a per-action way to save it until
  			 * then, thus var_str.
  			 */
  			char			*var_str;

  			/*
  			 * var_ref refers to the variable being
  			 * tracked e.g onmax($var).
  			 */
  			struct hist_field	*var_ref;

  			/*
  			 * track_var contains the 'invisible' tracking
  			 * variable created to keep the current
  			 * e.g. max value.
  			 */
  			struct hist_field	*track_var;

  			check_track_val_fn_t	check_val;
  			action_fn_t		save_data;
  		} track_data;
  	};
  };

  struct track_data {
  	u64				track_val;
  	bool				updated;

  	unsigned int			key_len;
  	void				*key;
  	struct tracing_map_elt		elt;

  	struct action_data		*action_data;
  	struct hist_trigger_data	*hist_data;
  };

  struct hist_elt_data {
  	char *comm;
  	u64 *var_ref_vals;
  	char *field_var_str[SYNTH_FIELDS_MAX];
  };

  struct snapshot_context {
  	struct tracing_map_elt	*elt;
  	void			*key;
  };

  static void track_data_free(struct track_data *track_data)
  {
  	struct hist_elt_data *elt_data;

  	if (!track_data)
  		return;

  	kfree(track_data->key);
  
  	elt_data = track_data->elt.private_data;
  	if (elt_data) {
  		kfree(elt_data->comm);
  		kfree(elt_data);

  	}

  	kfree(track_data);

  }

  static struct track_data *track_data_alloc(unsigned int key_len,
  					   struct action_data *action_data,
  					   struct hist_trigger_data *hist_data)

  {

  	struct track_data *data = kzalloc(sizeof(*data), GFP_KERNEL);
  	struct hist_elt_data *elt_data;

  	if (!data)
  		return ERR_PTR(-ENOMEM);

  	data->key = kzalloc(key_len, GFP_KERNEL);
  	if (!data->key) {
  		track_data_free(data);
  		return ERR_PTR(-ENOMEM);
  	}

  	data->key_len = key_len;
  	data->action_data = action_data;
  	data->hist_data = hist_data;

  	elt_data = kzalloc(sizeof(*elt_data), GFP_KERNEL);
  	if (!elt_data) {
  		track_data_free(data);
  		return ERR_PTR(-ENOMEM);
  	}

  	data->elt.private_data = elt_data;

  	elt_data->comm = kzalloc(TASK_COMM_LEN, GFP_KERNEL);
  	if (!elt_data->comm) {
  		track_data_free(data);
  		return ERR_PTR(-ENOMEM);

  	}

  	return data;
  }

  static char last_cmd[MAX_FILTER_STR_VAL];
  static char last_cmd_loc[MAX_FILTER_STR_VAL];

  static int errpos(char *str)
  {
  	return err_pos(last_cmd, str);

  }

  static void last_cmd_set(struct trace_event_file *file, char *str)

  {

  	const char *system = NULL, *name = NULL;
  	struct trace_event_call *call;

  	if (!str)
  		return;

  	strcpy(last_cmd, "hist:");
  	strncat(last_cmd, str, MAX_FILTER_STR_VAL - 1 - sizeof("hist:"));

  	if (file) {
  		call = file->event_call;
  		system = call->class->system;
  		if (system) {
  			name = trace_event_name(call);
  			if (!name)
  				system = NULL;
  		}

  	}

  	if (system)
  		snprintf(last_cmd_loc, MAX_FILTER_STR_VAL, "hist:%s:%s", system, name);

  }

  static void hist_err(struct trace_array *tr, u8 err_type, u8 err_pos)

  {

  	tracing_log_err(tr, last_cmd_loc, last_cmd, err_text,
  			err_type, err_pos);

  }

  static void hist_err_clear(void)

  {

  	last_cmd[0] = '\0';
  	last_cmd_loc[0] = '\0';

  }

  typedef void (*synth_probe_func_t) (void *__data, u64 *var_ref_vals,
  				    unsigned int *var_ref_idx);

  static inline void trace_synth(struct synth_event *event, u64 *var_ref_vals,
  			       unsigned int *var_ref_idx)

  {

  	struct tracepoint *tp = event->tp;

  	if (unlikely(atomic_read(&tp->key.enabled) > 0)) {
  		struct tracepoint_func *probe_func_ptr;
  		synth_probe_func_t probe_func;
  		void *__data;

  		if (!(cpu_online(raw_smp_processor_id())))
  			return;

  		probe_func_ptr = rcu_dereference_sched((tp)->funcs);
  		if (probe_func_ptr) {
  			do {
  				probe_func = probe_func_ptr->func;
  				__data = probe_func_ptr->data;
  				probe_func(__data, var_ref_vals, var_ref_idx);
  			} while ((++probe_func_ptr)->func);
  		}
  	}

  }

  static void action_trace(struct hist_trigger_data *hist_data,
  			 struct tracing_map_elt *elt, void *rec,
  			 struct ring_buffer_event *rbe, void *key,
  			 struct action_data *data, u64 *var_ref_vals)

  {

  	struct synth_event *event = data->synth_event;
  
  	trace_synth(event, var_ref_vals, data->var_ref_idx);

  }

  struct hist_var_data {
  	struct list_head list;
  	struct hist_trigger_data *hist_data;

  };

  static u64 hist_field_timestamp(struct hist_field *hist_field,
  				struct tracing_map_elt *elt,
  				struct ring_buffer_event *rbe,
  				void *event)

  {
  	struct hist_trigger_data *hist_data = hist_field->hist_data;
  	struct trace_array *tr = hist_data->event_file->tr;
  
  	u64 ts = ring_buffer_event_time_stamp(rbe);
  
  	if (hist_data->attrs->ts_in_usecs && trace_clock_in_ns(tr))
  		ts = ns2usecs(ts);
  
  	return ts;
  }

  static u64 hist_field_cpu(struct hist_field *hist_field,
  			  struct tracing_map_elt *elt,
  			  struct ring_buffer_event *rbe,
  			  void *event)
  {
  	int cpu = smp_processor_id();
  
  	return cpu;
  }

  /**
   * check_field_for_var_ref - Check if a VAR_REF field references a variable
   * @hist_field: The VAR_REF field to check
   * @var_data: The hist trigger that owns the variable
   * @var_idx: The trigger variable identifier
   *
   * Check the given VAR_REF field to see whether or not it references
   * the given variable associated with the given trigger.
   *
   * Return: The VAR_REF field if it does reference the variable, NULL if not
   */

  static struct hist_field *
  check_field_for_var_ref(struct hist_field *hist_field,
  			struct hist_trigger_data *var_data,
  			unsigned int var_idx)
  {

  	WARN_ON(!(hist_field && hist_field->flags & HIST_FIELD_FL_VAR_REF));

  	if (hist_field && hist_field->var.idx == var_idx &&
  	    hist_field->var.hist_data == var_data)
  		return hist_field;

  	return NULL;

  }

  /**
   * find_var_ref - Check if a trigger has a reference to a trigger variable
   * @hist_data: The hist trigger that might have a reference to the variable
   * @var_data: The hist trigger that owns the variable
   * @var_idx: The trigger variable identifier
   *
   * Check the list of var_refs[] on the first hist trigger to see
   * whether any of them are references to the variable on the second
   * trigger.
   *
   * Return: The VAR_REF field referencing the variable if so, NULL if not
   */

  static struct hist_field *find_var_ref(struct hist_trigger_data *hist_data,
  				       struct hist_trigger_data *var_data,
  				       unsigned int var_idx)
  {

  	struct hist_field *hist_field;

  	unsigned int i;

  	for (i = 0; i < hist_data->n_var_refs; i++) {
  		hist_field = hist_data->var_refs[i];
  		if (check_field_for_var_ref(hist_field, var_data, var_idx))
  			return hist_field;

  	}

  	return NULL;

  }

  /**
   * find_any_var_ref - Check if there is a reference to a given trigger variable
   * @hist_data: The hist trigger
   * @var_idx: The trigger variable identifier
   *
   * Check to see whether the given variable is currently referenced by
   * any other trigger.
   *
   * The trigger the variable is defined on is explicitly excluded - the
   * assumption being that a self-reference doesn't prevent a trigger
   * from being removed.
   *
   * Return: The VAR_REF field referencing the variable if so, NULL if not
   */

  static struct hist_field *find_any_var_ref(struct hist_trigger_data *hist_data,
  					   unsigned int var_idx)
  {
  	struct trace_array *tr = hist_data->event_file->tr;
  	struct hist_field *found = NULL;
  	struct hist_var_data *var_data;
  
  	list_for_each_entry(var_data, &tr->hist_vars, list) {
  		if (var_data->hist_data == hist_data)
  			continue;
  		found = find_var_ref(var_data->hist_data, hist_data, var_idx);
  		if (found)
  			break;
  	}
  
  	return found;
  }

  /**
   * check_var_refs - Check if there is a reference to any of trigger's variables
   * @hist_data: The hist trigger
   *
   * A trigger can define one or more variables.  If any one of them is
   * currently referenced by any other trigger, this function will
   * determine that.
  
   * Typically used to determine whether or not a trigger can be removed
   * - if there are any references to a trigger's variables, it cannot.
   *
   * Return: True if there is a reference to any of trigger's variables
   */

  static bool check_var_refs(struct hist_trigger_data *hist_data)
  {
  	struct hist_field *field;
  	bool found = false;
  	int i;
  
  	for_each_hist_field(i, hist_data) {
  		field = hist_data->fields[i];
  		if (field && field->flags & HIST_FIELD_FL_VAR) {
  			if (find_any_var_ref(hist_data, field->var.idx)) {
  				found = true;
  				break;
  			}
  		}
  	}
  
  	return found;
  }
  
  static struct hist_var_data *find_hist_vars(struct hist_trigger_data *hist_data)
  {
  	struct trace_array *tr = hist_data->event_file->tr;
  	struct hist_var_data *var_data, *found = NULL;
  
  	list_for_each_entry(var_data, &tr->hist_vars, list) {
  		if (var_data->hist_data == hist_data) {
  			found = var_data;
  			break;
  		}
  	}
  
  	return found;
  }
  
  static bool field_has_hist_vars(struct hist_field *hist_field,
  				unsigned int level)
  {
  	int i;
  
  	if (level > 3)
  		return false;
  
  	if (!hist_field)
  		return false;
  
  	if (hist_field->flags & HIST_FIELD_FL_VAR ||
  	    hist_field->flags & HIST_FIELD_FL_VAR_REF)
  		return true;
  
  	for (i = 0; i < HIST_FIELD_OPERANDS_MAX; i++) {
  		struct hist_field *operand;
  
  		operand = hist_field->operands[i];
  		if (field_has_hist_vars(operand, level + 1))
  			return true;
  	}
  
  	return false;
  }
  
  static bool has_hist_vars(struct hist_trigger_data *hist_data)
  {
  	struct hist_field *hist_field;
  	int i;
  
  	for_each_hist_field(i, hist_data) {
  		hist_field = hist_data->fields[i];
  		if (field_has_hist_vars(hist_field, 0))
  			return true;
  	}
  
  	return false;
  }
  
  static int save_hist_vars(struct hist_trigger_data *hist_data)
  {
  	struct trace_array *tr = hist_data->event_file->tr;
  	struct hist_var_data *var_data;
  
  	var_data = find_hist_vars(hist_data);
  	if (var_data)
  		return 0;

  	if (tracing_check_open_get_tr(tr))

  		return -ENODEV;
  
  	var_data = kzalloc(sizeof(*var_data), GFP_KERNEL);
  	if (!var_data) {
  		trace_array_put(tr);
  		return -ENOMEM;
  	}
  
  	var_data->hist_data = hist_data;
  	list_add(&var_data->list, &tr->hist_vars);
  
  	return 0;
  }
  
  static void remove_hist_vars(struct hist_trigger_data *hist_data)
  {
  	struct trace_array *tr = hist_data->event_file->tr;
  	struct hist_var_data *var_data;
  
  	var_data = find_hist_vars(hist_data);
  	if (!var_data)
  		return;
  
  	if (WARN_ON(check_var_refs(hist_data)))
  		return;
  
  	list_del(&var_data->list);
  
  	kfree(var_data);
  
  	trace_array_put(tr);
  }

  static struct hist_field *find_var_field(struct hist_trigger_data *hist_data,
  					 const char *var_name)
  {
  	struct hist_field *hist_field, *found = NULL;
  	int i;
  
  	for_each_hist_field(i, hist_data) {
  		hist_field = hist_data->fields[i];
  		if (hist_field && hist_field->flags & HIST_FIELD_FL_VAR &&
  		    strcmp(hist_field->var.name, var_name) == 0) {
  			found = hist_field;
  			break;
  		}
  	}
  
  	return found;
  }
  
  static struct hist_field *find_var(struct hist_trigger_data *hist_data,
  				   struct trace_event_file *file,
  				   const char *var_name)
  {
  	struct hist_trigger_data *test_data;
  	struct event_trigger_data *test;
  	struct hist_field *hist_field;

  	lockdep_assert_held(&event_mutex);

  	hist_field = find_var_field(hist_data, var_name);
  	if (hist_field)
  		return hist_field;

  	list_for_each_entry(test, &file->triggers, list) {

  		if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
  			test_data = test->private_data;
  			hist_field = find_var_field(test_data, var_name);
  			if (hist_field)
  				return hist_field;
  		}
  	}
  
  	return NULL;
  }

  static struct trace_event_file *find_var_file(struct trace_array *tr,
  					      char *system,
  					      char *event_name,
  					      char *var_name)
  {
  	struct hist_trigger_data *var_hist_data;
  	struct hist_var_data *var_data;
  	struct trace_event_file *file, *found = NULL;
  
  	if (system)
  		return find_event_file(tr, system, event_name);
  
  	list_for_each_entry(var_data, &tr->hist_vars, list) {
  		var_hist_data = var_data->hist_data;
  		file = var_hist_data->event_file;
  		if (file == found)
  			continue;
  
  		if (find_var_field(var_hist_data, var_name)) {

  			if (found) {

  				hist_err(tr, HIST_ERR_VAR_NOT_UNIQUE, errpos(var_name));

  				return NULL;

  			}

  
  			found = file;
  		}
  	}
  
  	return found;
  }
  
  static struct hist_field *find_file_var(struct trace_event_file *file,
  					const char *var_name)
  {
  	struct hist_trigger_data *test_data;
  	struct event_trigger_data *test;
  	struct hist_field *hist_field;

  	lockdep_assert_held(&event_mutex);
  
  	list_for_each_entry(test, &file->triggers, list) {

  		if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
  			test_data = test->private_data;
  			hist_field = find_var_field(test_data, var_name);
  			if (hist_field)
  				return hist_field;
  		}
  	}
  
  	return NULL;
  }

  static struct hist_field *
  find_match_var(struct hist_trigger_data *hist_data, char *var_name)
  {
  	struct trace_array *tr = hist_data->event_file->tr;
  	struct hist_field *hist_field, *found = NULL;
  	struct trace_event_file *file;
  	unsigned int i;
  
  	for (i = 0; i < hist_data->n_actions; i++) {
  		struct action_data *data = hist_data->actions[i];

  		if (data->handler == HANDLER_ONMATCH) {

  			char *system = data->match_data.event_system;
  			char *event_name = data->match_data.event;

  
  			file = find_var_file(tr, system, event_name, var_name);
  			if (!file)
  				continue;
  			hist_field = find_file_var(file, var_name);
  			if (hist_field) {
  				if (found) {

  					hist_err(tr, HIST_ERR_VAR_NOT_UNIQUE,
  						 errpos(var_name));

  					return ERR_PTR(-EINVAL);
  				}
  
  				found = hist_field;
  			}
  		}
  	}
  	return found;
  }

  static struct hist_field *find_event_var(struct hist_trigger_data *hist_data,
  					 char *system,
  					 char *event_name,
  					 char *var_name)
  {
  	struct trace_array *tr = hist_data->event_file->tr;
  	struct hist_field *hist_field = NULL;
  	struct trace_event_file *file;

  	if (!system || !event_name) {
  		hist_field = find_match_var(hist_data, var_name);
  		if (IS_ERR(hist_field))
  			return NULL;
  		if (hist_field)
  			return hist_field;
  	}

  	file = find_var_file(tr, system, event_name, var_name);
  	if (!file)
  		return NULL;
  
  	hist_field = find_file_var(file, var_name);
  
  	return hist_field;
  }

  static u64 hist_field_var_ref(struct hist_field *hist_field,
  			      struct tracing_map_elt *elt,
  			      struct ring_buffer_event *rbe,
  			      void *event)
  {
  	struct hist_elt_data *elt_data;
  	u64 var_val = 0;

  	if (WARN_ON_ONCE(!elt))
  		return var_val;

  	elt_data = elt->private_data;
  	var_val = elt_data->var_ref_vals[hist_field->var_ref_idx];
  
  	return var_val;
  }
  
  static bool resolve_var_refs(struct hist_trigger_data *hist_data, void *key,
  			     u64 *var_ref_vals, bool self)
  {
  	struct hist_trigger_data *var_data;
  	struct tracing_map_elt *var_elt;
  	struct hist_field *hist_field;
  	unsigned int i, var_idx;
  	bool resolved = true;
  	u64 var_val = 0;
  
  	for (i = 0; i < hist_data->n_var_refs; i++) {
  		hist_field = hist_data->var_refs[i];
  		var_idx = hist_field->var.idx;
  		var_data = hist_field->var.hist_data;
  
  		if (var_data == NULL) {
  			resolved = false;
  			break;
  		}
  
  		if ((self && var_data != hist_data) ||
  		    (!self && var_data == hist_data))
  			continue;
  
  		var_elt = tracing_map_lookup(var_data->map, key);
  		if (!var_elt) {
  			resolved = false;
  			break;
  		}
  
  		if (!tracing_map_var_set(var_elt, var_idx)) {
  			resolved = false;
  			break;
  		}
  
  		if (self || !hist_field->read_once)
  			var_val = tracing_map_read_var(var_elt, var_idx);
  		else
  			var_val = tracing_map_read_var_once(var_elt, var_idx);
  
  		var_ref_vals[i] = var_val;
  	}
  
  	return resolved;
  }

  static const char *hist_field_name(struct hist_field *field,
  				   unsigned int level)
  {
  	const char *field_name = "";
  
  	if (level > 1)
  		return field_name;
  
  	if (field->field)
  		field_name = field->field->name;

  	else if (field->flags & HIST_FIELD_FL_LOG2 ||
  		 field->flags & HIST_FIELD_FL_ALIAS)

  		field_name = hist_field_name(field->operands[0], ++level);

  	else if (field->flags & HIST_FIELD_FL_CPU)
  		field_name = "cpu";

  	else if (field->flags & HIST_FIELD_FL_EXPR ||
  		 field->flags & HIST_FIELD_FL_VAR_REF) {
  		if (field->system) {
  			static char full_name[MAX_FILTER_STR_VAL];
  
  			strcat(full_name, field->system);
  			strcat(full_name, ".");
  			strcat(full_name, field->event_name);
  			strcat(full_name, ".");
  			strcat(full_name, field->name);
  			field_name = full_name;
  		} else
  			field_name = field->name;

  	} else if (field->flags & HIST_FIELD_FL_TIMESTAMP)
  		field_name = "common_timestamp";

  
  	if (field_name == NULL)
  		field_name = "";
  
  	return field_name;
  }

  static hist_field_fn_t select_value_fn(int field_size, int field_is_signed)
  {
  	hist_field_fn_t fn = NULL;
  
  	switch (field_size) {
  	case 8:
  		if (field_is_signed)
  			fn = hist_field_s64;
  		else
  			fn = hist_field_u64;
  		break;
  	case 4:
  		if (field_is_signed)
  			fn = hist_field_s32;
  		else
  			fn = hist_field_u32;
  		break;
  	case 2:
  		if (field_is_signed)
  			fn = hist_field_s16;
  		else
  			fn = hist_field_u16;
  		break;
  	case 1:
  		if (field_is_signed)
  			fn = hist_field_s8;
  		else
  			fn = hist_field_u8;
  		break;
  	}
  
  	return fn;
  }
  
  static int parse_map_size(char *str)
  {
  	unsigned long size, map_bits;
  	int ret;

  	ret = kstrtoul(str, 0, &size);
  	if (ret)
  		goto out;
  
  	map_bits = ilog2(roundup_pow_of_two(size));
  	if (map_bits < TRACING_MAP_BITS_MIN ||
  	    map_bits > TRACING_MAP_BITS_MAX)
  		ret = -EINVAL;
  	else
  		ret = map_bits;
   out:
  	return ret;
  }
  
  static void destroy_hist_trigger_attrs(struct hist_trigger_attrs *attrs)
  {

  	unsigned int i;

  	if (!attrs)
  		return;

  	for (i = 0; i < attrs->n_assignments; i++)
  		kfree(attrs->assignment_str[i]);

  	for (i = 0; i < attrs->n_actions; i++)
  		kfree(attrs->action_str[i]);

  	kfree(attrs->name);

  	kfree(attrs->sort_key_str);

  	kfree(attrs->keys_str);

  	kfree(attrs->vals_str);

  	kfree(attrs->clock);

  	kfree(attrs);
  }

  static int parse_action(char *str, struct hist_trigger_attrs *attrs)
  {

  	int ret = -EINVAL;

  
  	if (attrs->n_actions >= HIST_ACTIONS_MAX)
  		return ret;

  	if ((str_has_prefix(str, "onmatch(")) ||

  	    (str_has_prefix(str, "onmax(")) ||
  	    (str_has_prefix(str, "onchange("))) {

  		attrs->action_str[attrs->n_actions] = kstrdup(str, GFP_KERNEL);
  		if (!attrs->action_str[attrs->n_actions]) {
  			ret = -ENOMEM;
  			return ret;
  		}
  		attrs->n_actions++;
  		ret = 0;
  	}

  	return ret;
  }

  static int parse_assignment(struct trace_array *tr,
  			    char *str, struct hist_trigger_attrs *attrs)

  {

  	int len, ret = 0;

  	if ((len = str_has_prefix(str, "key=")) ||
  	    (len = str_has_prefix(str, "keys="))) {
  		attrs->keys_str = kstrdup(str + len, GFP_KERNEL);

  		if (!attrs->keys_str) {
  			ret = -ENOMEM;
  			goto out;
  		}

  	} else if ((len = str_has_prefix(str, "val=")) ||
  		   (len = str_has_prefix(str, "vals=")) ||
  		   (len = str_has_prefix(str, "values="))) {
  		attrs->vals_str = kstrdup(str + len, GFP_KERNEL);

  		if (!attrs->vals_str) {
  			ret = -ENOMEM;
  			goto out;
  		}

  	} else if ((len = str_has_prefix(str, "sort="))) {
  		attrs->sort_key_str = kstrdup(str + len, GFP_KERNEL);

  		if (!attrs->sort_key_str) {
  			ret = -ENOMEM;
  			goto out;
  		}

  	} else if (str_has_prefix(str, "name=")) {

  		attrs->name = kstrdup(str, GFP_KERNEL);
  		if (!attrs->name) {
  			ret = -ENOMEM;
  			goto out;
  		}

  	} else if ((len = str_has_prefix(str, "clock="))) {
  		str += len;

  
  		str = strstrip(str);
  		attrs->clock = kstrdup(str, GFP_KERNEL);
  		if (!attrs->clock) {
  			ret = -ENOMEM;
  			goto out;
  		}

  	} else if ((len = str_has_prefix(str, "size="))) {
  		int map_bits = parse_map_size(str + len);

  
  		if (map_bits < 0) {
  			ret = map_bits;
  			goto out;
  		}
  		attrs->map_bits = map_bits;

  	} else {
  		char *assignment;
  
  		if (attrs->n_assignments == TRACING_MAP_VARS_MAX) {

  			hist_err(tr, HIST_ERR_TOO_MANY_VARS, errpos(str));

  			ret = -EINVAL;
  			goto out;
  		}
  
  		assignment = kstrdup(str, GFP_KERNEL);
  		if (!assignment) {
  			ret = -ENOMEM;
  			goto out;
  		}
  
  		attrs->assignment_str[attrs->n_assignments++] = assignment;
  	}

   out:
  	return ret;
  }

  static struct hist_trigger_attrs *
  parse_hist_trigger_attrs(struct trace_array *tr, char *trigger_str)

  {
  	struct hist_trigger_attrs *attrs;
  	int ret = 0;
  
  	attrs = kzalloc(sizeof(*attrs), GFP_KERNEL);
  	if (!attrs)
  		return ERR_PTR(-ENOMEM);
  
  	while (trigger_str) {
  		char *str = strsep(&trigger_str, ":");

  		char *rhs;

  		rhs = strchr(str, '=');
  		if (rhs) {
  			if (!strlen(++rhs)) {
  				ret = -EINVAL;

  				hist_err(tr, HIST_ERR_EMPTY_ASSIGNMENT, errpos(str));

  				goto free;
  			}

  			ret = parse_assignment(tr, str, attrs);

  			if (ret)
  				goto free;
  		} else if (strcmp(str, "pause") == 0)

  			attrs->pause = true;
  		else if ((strcmp(str, "cont") == 0) ||
  			 (strcmp(str, "continue") == 0))
  			attrs->cont = true;

  		else if (strcmp(str, "clear") == 0)
  			attrs->clear = true;

  		else {

  			ret = parse_action(str, attrs);
  			if (ret)
  				goto free;

  		}
  	}
  
  	if (!attrs->keys_str) {
  		ret = -EINVAL;
  		goto free;
  	}

  	if (!attrs->clock) {
  		attrs->clock = kstrdup("global", GFP_KERNEL);
  		if (!attrs->clock) {
  			ret = -ENOMEM;
  			goto free;
  		}
  	}

  	return attrs;
   free:
  	destroy_hist_trigger_attrs(attrs);
  
  	return ERR_PTR(ret);
  }

  static inline void save_comm(char *comm, struct task_struct *task)
  {
  	if (!task->pid) {
  		strcpy(comm, "<idle>");
  		return;
  	}
  
  	if (WARN_ON_ONCE(task->pid < 0)) {
  		strcpy(comm, "<XXX>");
  		return;
  	}

  	strncpy(comm, task->comm, TASK_COMM_LEN);

  }

  static void hist_elt_data_free(struct hist_elt_data *elt_data)
  {

  	unsigned int i;
  
  	for (i = 0; i < SYNTH_FIELDS_MAX; i++)
  		kfree(elt_data->field_var_str[i]);

  	kfree(elt_data->comm);
  	kfree(elt_data);
  }
  
  static void hist_trigger_elt_data_free(struct tracing_map_elt *elt)

  {

  	struct hist_elt_data *elt_data = elt->private_data;
  
  	hist_elt_data_free(elt_data);

  }

  static int hist_trigger_elt_data_alloc(struct tracing_map_elt *elt)

  {
  	struct hist_trigger_data *hist_data = elt->map->private_data;

  	unsigned int size = TASK_COMM_LEN;
  	struct hist_elt_data *elt_data;

  	struct hist_field *key_field;

  	unsigned int i, n_str;

  	elt_data = kzalloc(sizeof(*elt_data), GFP_KERNEL);
  	if (!elt_data)
  		return -ENOMEM;

  	for_each_hist_key_field(i, hist_data) {
  		key_field = hist_data->fields[i];
  
  		if (key_field->flags & HIST_FIELD_FL_EXECNAME) {

  			elt_data->comm = kzalloc(size, GFP_KERNEL);
  			if (!elt_data->comm) {
  				kfree(elt_data);

  				return -ENOMEM;

  			}

  			break;
  		}
  	}

  	n_str = hist_data->n_field_var_str + hist_data->n_save_var_str +
  		hist_data->n_var_str;
  	if (n_str > SYNTH_FIELDS_MAX) {
  		hist_elt_data_free(elt_data);
  		return -EINVAL;
  	}

  	BUILD_BUG_ON(STR_VAR_LEN_MAX & (sizeof(u64) - 1));

  	size = STR_VAR_LEN_MAX;
  
  	for (i = 0; i < n_str; i++) {
  		elt_data->field_var_str[i] = kzalloc(size, GFP_KERNEL);
  		if (!elt_data->field_var_str[i]) {
  			hist_elt_data_free(elt_data);
  			return -ENOMEM;
  		}
  	}

  	elt->private_data = elt_data;

  	return 0;
  }

  static void hist_trigger_elt_data_init(struct tracing_map_elt *elt)

  {

  	struct hist_elt_data *elt_data = elt->private_data;

  	if (elt_data->comm)
  		save_comm(elt_data->comm, current);

  }

  static const struct tracing_map_ops hist_trigger_elt_data_ops = {
  	.elt_alloc	= hist_trigger_elt_data_alloc,
  	.elt_free	= hist_trigger_elt_data_free,
  	.elt_init	= hist_trigger_elt_data_init,

  };

  static const char *get_hist_field_flags(struct hist_field *hist_field)
  {
  	const char *flags_str = NULL;
  
  	if (hist_field->flags & HIST_FIELD_FL_HEX)
  		flags_str = "hex";
  	else if (hist_field->flags & HIST_FIELD_FL_SYM)
  		flags_str = "sym";
  	else if (hist_field->flags & HIST_FIELD_FL_SYM_OFFSET)
  		flags_str = "sym-offset";
  	else if (hist_field->flags & HIST_FIELD_FL_EXECNAME)
  		flags_str = "execname";
  	else if (hist_field->flags & HIST_FIELD_FL_SYSCALL)
  		flags_str = "syscall";
  	else if (hist_field->flags & HIST_FIELD_FL_LOG2)
  		flags_str = "log2";
  	else if (hist_field->flags & HIST_FIELD_FL_TIMESTAMP_USECS)
  		flags_str = "usecs";
  
  	return flags_str;
  }

  static void expr_field_str(struct hist_field *field, char *expr)
  {

  	if (field->flags & HIST_FIELD_FL_VAR_REF)
  		strcat(expr, "$");

  	strcat(expr, hist_field_name(field, 0));

  	if (field->flags && !(field->flags & HIST_FIELD_FL_VAR_REF)) {

  		const char *flags_str = get_hist_field_flags(field);
  
  		if (flags_str) {
  			strcat(expr, ".");
  			strcat(expr, flags_str);
  		}
  	}
  }
  
  static char *expr_str(struct hist_field *field, unsigned int level)
  {
  	char *expr;
  
  	if (level > 1)
  		return NULL;
  
  	expr = kzalloc(MAX_FILTER_STR_VAL, GFP_KERNEL);
  	if (!expr)
  		return NULL;
  
  	if (!field->operands[0]) {
  		expr_field_str(field, expr);
  		return expr;
  	}
  
  	if (field->operator == FIELD_OP_UNARY_MINUS) {
  		char *subexpr;
  
  		strcat(expr, "-(");
  		subexpr = expr_str(field->operands[0], ++level);
  		if (!subexpr) {
  			kfree(expr);
  			return NULL;
  		}
  		strcat(expr, subexpr);
  		strcat(expr, ")");
  
  		kfree(subexpr);
  
  		return expr;
  	}
  
  	expr_field_str(field->operands[0], expr);
  
  	switch (field->operator) {
  	case FIELD_OP_MINUS:
  		strcat(expr, "-");
  		break;
  	case FIELD_OP_PLUS:
  		strcat(expr, "+");
  		break;
  	default:
  		kfree(expr);
  		return NULL;
  	}
  
  	expr_field_str(field->operands[1], expr);
  
  	return expr;
  }
  
  static int contains_operator(char *str)
  {
  	enum field_op_id field_op = FIELD_OP_NONE;
  	char *op;
  
  	op = strpbrk(str, "+-");
  	if (!op)
  		return FIELD_OP_NONE;
  
  	switch (*op) {
  	case '-':
  		if (*str == '-')
  			field_op = FIELD_OP_UNARY_MINUS;
  		else
  			field_op = FIELD_OP_MINUS;
  		break;
  	case '+':
  		field_op = FIELD_OP_PLUS;
  		break;
  	default:
  		break;
  	}
  
  	return field_op;
  }

  static void get_hist_field(struct hist_field *hist_field)
  {
  	hist_field->ref++;
  }

  static void __destroy_hist_field(struct hist_field *hist_field)
  {

  	if (--hist_field->ref > 1)
  		return;

  	kfree(hist_field->var.name);
  	kfree(hist_field->name);
  	kfree(hist_field->type);

  	kfree(hist_field->system);
  	kfree(hist_field->event_name);

  	kfree(hist_field);
  }

  static void destroy_hist_field(struct hist_field *hist_field,
  			       unsigned int level)

  {

  	unsigned int i;

  	if (level > 3)

  		return;
  
  	if (!hist_field)
  		return;

  	if (hist_field->flags & HIST_FIELD_FL_VAR_REF)
  		return; /* var refs will be destroyed separately */

  	for (i = 0; i < HIST_FIELD_OPERANDS_MAX; i++)
  		destroy_hist_field(hist_field->operands[i], level + 1);

  	__destroy_hist_field(hist_field);

  }

  static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
  					    struct ftrace_event_field *field,

  					    unsigned long flags,
  					    char *var_name)

  {
  	struct hist_field *hist_field;
  
  	if (field && is_function_field(field))
  		return NULL;
  
  	hist_field = kzalloc(sizeof(struct hist_field), GFP_KERNEL);
  	if (!hist_field)
  		return NULL;

  	hist_field->ref = 1;

  	hist_field->hist_data = hist_data;

  	if (flags & HIST_FIELD_FL_EXPR || flags & HIST_FIELD_FL_ALIAS)

  		goto out; /* caller will populate */

  	if (flags & HIST_FIELD_FL_VAR_REF) {
  		hist_field->fn = hist_field_var_ref;
  		goto out;
  	}

  	if (flags & HIST_FIELD_FL_HITCOUNT) {
  		hist_field->fn = hist_field_counter;

  		hist_field->size = sizeof(u64);
  		hist_field->type = kstrdup("u64", GFP_KERNEL);
  		if (!hist_field->type)
  			goto free;

  		goto out;
  	}

  	if (flags & HIST_FIELD_FL_STACKTRACE) {
  		hist_field->fn = hist_field_none;
  		goto out;
  	}

  	if (flags & HIST_FIELD_FL_LOG2) {

  		unsigned long fl = flags & ~HIST_FIELD_FL_LOG2;

  		hist_field->fn = hist_field_log2;

  		hist_field->operands[0] = create_hist_field(hist_data, field, fl, NULL);

  		hist_field->size = hist_field->operands[0]->size;

  		hist_field->type = kstrdup(hist_field->operands[0]->type, GFP_KERNEL);
  		if (!hist_field->type)
  			goto free;

  		goto out;
  	}

  	if (flags & HIST_FIELD_FL_TIMESTAMP) {
  		hist_field->fn = hist_field_timestamp;
  		hist_field->size = sizeof(u64);

  		hist_field->type = kstrdup("u64", GFP_KERNEL);
  		if (!hist_field->type)
  			goto free;

  		goto out;
  	}

  	if (flags & HIST_FIELD_FL_CPU) {
  		hist_field->fn = hist_field_cpu;
  		hist_field->size = sizeof(int);
  		hist_field->type = kstrdup("unsigned int", GFP_KERNEL);
  		if (!hist_field->type)
  			goto free;
  		goto out;
  	}

  	if (WARN_ON_ONCE(!field))
  		goto out;

  	if (is_string_field(field)) {
  		flags |= HIST_FIELD_FL_STRING;

  		hist_field->size = MAX_FILTER_STR_VAL;
  		hist_field->type = kstrdup(field->type, GFP_KERNEL);
  		if (!hist_field->type)
  			goto free;

  		if (field->filter_type == FILTER_STATIC_STRING)
  			hist_field->fn = hist_field_string;
  		else if (field->filter_type == FILTER_DYN_STRING)
  			hist_field->fn = hist_field_dynstring;
  		else
  			hist_field->fn = hist_field_pstring;

  	} else {

  		hist_field->size = field->size;
  		hist_field->is_signed = field->is_signed;
  		hist_field->type = kstrdup(field->type, GFP_KERNEL);
  		if (!hist_field->type)
  			goto free;

  		hist_field->fn = select_value_fn(field->size,
  						 field->is_signed);
  		if (!hist_field->fn) {

  			destroy_hist_field(hist_field, 0);

  			return NULL;
  		}
  	}
   out:
  	hist_field->field = field;
  	hist_field->flags = flags;

  	if (var_name) {
  		hist_field->var.name = kstrdup(var_name, GFP_KERNEL);
  		if (!hist_field->var.name)
  			goto free;
  	}

  	return hist_field;

   free:
  	destroy_hist_field(hist_field, 0);
  	return NULL;

  }
  
  static void destroy_hist_fields(struct hist_trigger_data *hist_data)
  {
  	unsigned int i;

  	for (i = 0; i < HIST_FIELDS_MAX; i++) {

  		if (hist_data->fields[i]) {

  			destroy_hist_field(hist_data->fields[i], 0);

  			hist_data->fields[i] = NULL;
  		}
  	}

  
  	for (i = 0; i < hist_data->n_var_refs; i++) {
  		WARN_ON(!(hist_data->var_refs[i]->flags & HIST_FIELD_FL_VAR_REF));
  		__destroy_hist_field(hist_data->var_refs[i]);
  		hist_data->var_refs[i] = NULL;
  	}

  }

  static int init_var_ref(struct hist_field *ref_field,
  			struct hist_field *var_field,
  			char *system, char *event_name)
  {
  	int err = 0;
  
  	ref_field->var.idx = var_field->var.idx;
  	ref_field->var.hist_data = var_field->hist_data;
  	ref_field->size = var_field->size;
  	ref_field->is_signed = var_field->is_signed;
  	ref_field->flags |= var_field->flags &
  		(HIST_FIELD_FL_TIMESTAMP | HIST_FIELD_FL_TIMESTAMP_USECS);
  
  	if (system) {
  		ref_field->system = kstrdup(system, GFP_KERNEL);
  		if (!ref_field->system)
  			return -ENOMEM;
  	}
  
  	if (event_name) {
  		ref_field->event_name = kstrdup(event_name, GFP_KERNEL);
  		if (!ref_field->event_name) {
  			err = -ENOMEM;
  			goto free;
  		}
  	}

  	if (var_field->var.name) {
  		ref_field->name = kstrdup(var_field->var.name, GFP_KERNEL);
  		if (!ref_field->name) {
  			err = -ENOMEM;
  			goto free;
  		}
  	} else if (var_field->name) {
  		ref_field->name = kstrdup(var_field->name, GFP_KERNEL);
  		if (!ref_field->name) {
  			err = -ENOMEM;
  			goto free;
  		}

  	}
  
  	ref_field->type = kstrdup(var_field->type, GFP_KERNEL);
  	if (!ref_field->type) {
  		err = -ENOMEM;
  		goto free;
  	}
   out:
  	return err;
   free:
  	kfree(ref_field->system);
  	kfree(ref_field->event_name);
  	kfree(ref_field->name);
  
  	goto out;
  }

  static int find_var_ref_idx(struct hist_trigger_data *hist_data,
  			    struct hist_field *var_field)
  {
  	struct hist_field *ref_field;
  	int i;
  
  	for (i = 0; i < hist_data->n_var_refs; i++) {
  		ref_field = hist_data->var_refs[i];
  		if (ref_field->var.idx == var_field->var.idx &&
  		    ref_field->var.hist_data == var_field->hist_data)
  			return i;
  	}
  
  	return -ENOENT;
  }

  /**
   * create_var_ref - Create a variable reference and attach it to trigger
   * @hist_data: The trigger that will be referencing the variable
   * @var_field: The VAR field to create a reference to
   * @system: The optional system string
   * @event_name: The optional event_name string
   *
   * Given a variable hist_field, create a VAR_REF hist_field that
   * represents a reference to it.
   *
   * This function also adds the reference to the trigger that
   * now references the variable.
   *
   * Return: The VAR_REF field if successful, NULL if not
   */
  static struct hist_field *create_var_ref(struct hist_trigger_data *hist_data,
  					 struct hist_field *var_field,

  					 char *system, char *event_name)
  {
  	unsigned long flags = HIST_FIELD_FL_VAR_REF;
  	struct hist_field *ref_field;

  	int i;
  
  	/* Check if the variable already exists */
  	for (i = 0; i < hist_data->n_var_refs; i++) {
  		ref_field = hist_data->var_refs[i];
  		if (ref_field->var.idx == var_field->var.idx &&
  		    ref_field->var.hist_data == var_field->hist_data) {
  			get_hist_field(ref_field);
  			return ref_field;
  		}
  	}

  
  	ref_field = create_hist_field(var_field->hist_data, NULL, flags, NULL);
  	if (ref_field) {
  		if (init_var_ref(ref_field, var_field, system, event_name)) {
  			destroy_hist_field(ref_field, 0);
  			return NULL;
  		}

  
  		hist_data->var_refs[hist_data->n_var_refs] = ref_field;
  		ref_field->var_ref_idx = hist_data->n_var_refs++;

  	}
  
  	return ref_field;
  }
  
  static bool is_var_ref(char *var_name)
  {
  	if (!var_name || strlen(var_name) < 2 || var_name[0] != '$')
  		return false;
  
  	return true;
  }
  
  static char *field_name_from_var(struct hist_trigger_data *hist_data,
  				 char *var_name)
  {
  	char *name, *field;
  	unsigned int i;
  
  	for (i = 0; i < hist_data->attrs->var_defs.n_vars; i++) {
  		name = hist_data->attrs->var_defs.name[i];
  
  		if (strcmp(var_name, name) == 0) {
  			field = hist_data->attrs->var_defs.expr[i];
  			if (contains_operator(field) || is_var_ref(field))
  				continue;
  			return field;
  		}
  	}
  
  	return NULL;
  }
  
  static char *local_field_var_ref(struct hist_trigger_data *hist_data,
  				 char *system, char *event_name,
  				 char *var_name)
  {
  	struct trace_event_call *call;
  
  	if (system && event_name) {
  		call = hist_data->event_file->event_call;
  
  		if (strcmp(system, call->class->system) != 0)
  			return NULL;
  
  		if (strcmp(event_name, trace_event_name(call)) != 0)
  			return NULL;
  	}
  
  	if (!!system != !!event_name)
  		return NULL;
  
  	if (!is_var_ref(var_name))
  		return NULL;
  
  	var_name++;
  
  	return field_name_from_var(hist_data, var_name);
  }
  
  static struct hist_field *parse_var_ref(struct hist_trigger_data *hist_data,
  					char *system, char *event_name,
  					char *var_name)
  {
  	struct hist_field *var_field = NULL, *ref_field = NULL;

  	struct trace_array *tr = hist_data->event_file->tr;

  
  	if (!is_var_ref(var_name))
  		return NULL;
  
  	var_name++;
  
  	var_field = find_event_var(hist_data, system, event_name, var_name);
  	if (var_field)

  		ref_field = create_var_ref(hist_data, var_field,
  					   system, event_name);

  	if (!ref_field)

  		hist_err(tr, HIST_ERR_VAR_NOT_FOUND, errpos(var_name));

  	return ref_field;
  }

  static struct ftrace_event_field *
  parse_field(struct hist_trigger_data *hist_data, struct trace_event_file *file,
  	    char *field_str, unsigned long *flags)
  {
  	struct ftrace_event_field *field = NULL;
  	char *field_name, *modifier, *str;

  	struct trace_array *tr = file->tr;

  
  	modifier = str = kstrdup(field_str, GFP_KERNEL);
  	if (!modifier)
  		return ERR_PTR(-ENOMEM);
  
  	field_name = strsep(&modifier, ".");
  	if (modifier) {
  		if (strcmp(modifier, "hex") == 0)
  			*flags |= HIST_FIELD_FL_HEX;
  		else if (strcmp(modifier, "sym") == 0)
  			*flags |= HIST_FIELD_FL_SYM;
  		else if (strcmp(modifier, "sym-offset") == 0)
  			*flags |= HIST_FIELD_FL_SYM_OFFSET;
  		else if ((strcmp(modifier, "execname") == 0) &&
  			 (strcmp(field_name, "common_pid") == 0))
  			*flags |= HIST_FIELD_FL_EXECNAME;
  		else if (strcmp(modifier, "syscall") == 0)
  			*flags |= HIST_FIELD_FL_SYSCALL;
  		else if (strcmp(modifier, "log2") == 0)
  			*flags |= HIST_FIELD_FL_LOG2;
  		else if (strcmp(modifier, "usecs") == 0)
  			*flags |= HIST_FIELD_FL_TIMESTAMP_USECS;
  		else {

  			hist_err(tr, HIST_ERR_BAD_FIELD_MODIFIER, errpos(modifier));

  			field = ERR_PTR(-EINVAL);
  			goto out;
  		}
  	}
  
  	if (strcmp(field_name, "common_timestamp") == 0) {
  		*flags |= HIST_FIELD_FL_TIMESTAMP;
  		hist_data->enable_timestamps = true;
  		if (*flags & HIST_FIELD_FL_TIMESTAMP_USECS)
  			hist_data->attrs->ts_in_usecs = true;

  	} else if (strcmp(field_name, "cpu") == 0)
  		*flags |= HIST_FIELD_FL_CPU;
  	else {

  		field = trace_find_event_field(file->event_call, field_name);
  		if (!field || !field->size) {

  			hist_err(tr, HIST_ERR_FIELD_NOT_FOUND, errpos(field_name));

  			field = ERR_PTR(-EINVAL);
  			goto out;
  		}
  	}
   out:
  	kfree(str);
  
  	return field;
  }

  static struct hist_field *create_alias(struct hist_trigger_data *hist_data,
  				       struct hist_field *var_ref,
  				       char *var_name)
  {
  	struct hist_field *alias = NULL;
  	unsigned long flags = HIST_FIELD_FL_ALIAS | HIST_FIELD_FL_VAR;
  
  	alias = create_hist_field(hist_data, NULL, flags, var_name);
  	if (!alias)
  		return NULL;
  
  	alias->fn = var_ref->fn;
  	alias->operands[0] = var_ref;
  
  	if (init_var_ref(alias, var_ref, var_ref->system, var_ref->event_name)) {
  		destroy_hist_field(alias, 0);
  		return NULL;
  	}

  	alias->var_ref_idx = var_ref->var_ref_idx;

  	return alias;
  }

  static struct hist_field *parse_atom(struct hist_trigger_data *hist_data,
  				     struct trace_event_file *file, char *str,
  				     unsigned long *flags, char *var_name)
  {

  	char *s, *ref_system = NULL, *ref_event = NULL, *ref_var = str;

  	struct ftrace_event_field *field = NULL;
  	struct hist_field *hist_field = NULL;
  	int ret = 0;

  	s = strchr(str, '.');
  	if (s) {
  		s = strchr(++s, '.');
  		if (s) {
  			ref_system = strsep(&str, ".");
  			if (!str) {
  				ret = -EINVAL;
  				goto out;
  			}
  			ref_event = strsep(&str, ".");
  			if (!str) {
  				ret = -EINVAL;
  				goto out;
  			}
  			ref_var = str;
  		}
  	}
  
  	s = local_field_var_ref(hist_data, ref_system, ref_event, ref_var);
  	if (!s) {

  		hist_field = parse_var_ref(hist_data, ref_system,
  					   ref_event, ref_var);

  		if (hist_field) {

  			if (var_name) {
  				hist_field = create_alias(hist_data, hist_field, var_name);
  				if (!hist_field) {
  					ret = -ENOMEM;
  					goto out;
  				}
  			}

  			return hist_field;
  		}
  	} else
  		str = s;

  	field = parse_field(hist_data, file, str, flags);
  	if (IS_ERR(field)) {
  		ret = PTR_ERR(field);
  		goto out;
  	}
  
  	hist_field = create_hist_field(hist_data, field, *flags, var_name);
  	if (!hist_field) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	return hist_field;
   out:
  	return ERR_PTR(ret);
  }
  
  static struct hist_field *parse_expr(struct hist_trigger_data *hist_data,
  				     struct trace_event_file *file,
  				     char *str, unsigned long flags,
  				     char *var_name, unsigned int level);
  
  static struct hist_field *parse_unary(struct hist_trigger_data *hist_data,
  				      struct trace_event_file *file,
  				      char *str, unsigned long flags,
  				      char *var_name, unsigned int level)
  {
  	struct hist_field *operand1, *expr = NULL;
  	unsigned long operand_flags;
  	int ret = 0;
  	char *s;
  
  	/* we support only -(xxx) i.e. explicit parens required */
  
  	if (level > 3) {

  		hist_err(file->tr, HIST_ERR_TOO_MANY_SUBEXPR, errpos(str));

  		ret = -EINVAL;
  		goto free;
  	}
  
  	str++; /* skip leading '-' */
  
  	s = strchr(str, '(');
  	if (s)
  		str++;
  	else {
  		ret = -EINVAL;
  		goto free;
  	}
  
  	s = strrchr(str, ')');
  	if (s)
  		*s = '\0';
  	else {
  		ret = -EINVAL; /* no closing ')' */
  		goto free;
  	}
  
  	flags |= HIST_FIELD_FL_EXPR;
  	expr = create_hist_field(hist_data, NULL, flags, var_name);
  	if (!expr) {
  		ret = -ENOMEM;
  		goto free;
  	}
  
  	operand_flags = 0;
  	operand1 = parse_expr(hist_data, file, str, operand_flags, NULL, ++level);
  	if (IS_ERR(operand1)) {
  		ret = PTR_ERR(operand1);
  		goto free;
  	}
  
  	expr->flags |= operand1->flags &
  		(HIST_FIELD_FL_TIMESTAMP | HIST_FIELD_FL_TIMESTAMP_USECS);
  	expr->fn = hist_field_unary_minus;
  	expr->operands[0] = operand1;
  	expr->operator = FIELD_OP_UNARY_MINUS;
  	expr->name = expr_str(expr, 0);

  	expr->type = kstrdup(operand1->type, GFP_KERNEL);
  	if (!expr->type) {
  		ret = -ENOMEM;
  		goto free;
  	}

  
  	return expr;
   free:
  	destroy_hist_field(expr, 0);
  	return ERR_PTR(ret);
  }

  static int check_expr_operands(struct trace_array *tr,
  			       struct hist_field *operand1,

  			       struct hist_field *operand2)
  {
  	unsigned long operand1_flags = operand1->flags;
  	unsigned long operand2_flags = operand2->flags;

  	if ((operand1_flags & HIST_FIELD_FL_VAR_REF) ||
  	    (operand1_flags & HIST_FIELD_FL_ALIAS)) {
  		struct hist_field *var;
  
  		var = find_var_field(operand1->var.hist_data, operand1->name);
  		if (!var)
  			return -EINVAL;
  		operand1_flags = var->flags;
  	}
  
  	if ((operand2_flags & HIST_FIELD_FL_VAR_REF) ||
  	    (operand2_flags & HIST_FIELD_FL_ALIAS)) {
  		struct hist_field *var;
  
  		var = find_var_field(operand2->var.hist_data, operand2->name);
  		if (!var)
  			return -EINVAL;
  		operand2_flags = var->flags;
  	}

  	if ((operand1_flags & HIST_FIELD_FL_TIMESTAMP_USECS) !=

  	    (operand2_flags & HIST_FIELD_FL_TIMESTAMP_USECS)) {

  		hist_err(tr, HIST_ERR_TIMESTAMP_MISMATCH, 0);

  		return -EINVAL;

  	}

  
  	return 0;
  }
  
  static struct hist_field *parse_expr(struct hist_trigger_data *hist_data,
  				     struct trace_event_file *file,
  				     char *str, unsigned long flags,
  				     char *var_name, unsigned int level)
  {
  	struct hist_field *operand1 = NULL, *operand2 = NULL, *expr = NULL;
  	unsigned long operand_flags;
  	int field_op, ret = -EINVAL;
  	char *sep, *operand1_str;

  	if (level > 3) {

  		hist_err(file->tr, HIST_ERR_TOO_MANY_SUBEXPR, errpos(str));

  		return ERR_PTR(-EINVAL);

  	}

  
  	field_op = contains_operator(str);
  
  	if (field_op == FIELD_OP_NONE)
  		return parse_atom(hist_data, file, str, &flags, var_name);
  
  	if (field_op == FIELD_OP_UNARY_MINUS)
  		return parse_unary(hist_data, file, str, flags, var_name, ++level);
  
  	switch (field_op) {
  	case FIELD_OP_MINUS:
  		sep = "-";
  		break;
  	case FIELD_OP_PLUS:
  		sep = "+";
  		break;
  	default:
  		goto free;
  	}
  
  	operand1_str = strsep(&str, sep);
  	if (!operand1_str || !str)
  		goto free;
  
  	operand_flags = 0;
  	operand1 = parse_atom(hist_data, file, operand1_str,
  			      &operand_flags, NULL);
  	if (IS_ERR(operand1)) {
  		ret = PTR_ERR(operand1);
  		operand1 = NULL;
  		goto free;
  	}
  
  	/* rest of string could be another expression e.g. b+c in a+b+c */
  	operand_flags = 0;
  	operand2 = parse_expr(hist_data, file, str, operand_flags, NULL, ++level);
  	if (IS_ERR(operand2)) {
  		ret = PTR_ERR(operand2);
  		operand2 = NULL;
  		goto free;
  	}

  	ret = check_expr_operands(file->tr, operand1, operand2);

  	if (ret)
  		goto free;
  
  	flags |= HIST_FIELD_FL_EXPR;
  
  	flags |= operand1->flags &
  		(HIST_FIELD_FL_TIMESTAMP | HIST_FIELD_FL_TIMESTAMP_USECS);
  
  	expr = create_hist_field(hist_data, NULL, flags, var_name);
  	if (!expr) {
  		ret = -ENOMEM;
  		goto free;
  	}

  	operand1->read_once = true;
  	operand2->read_once = true;

  	expr->operands[0] = operand1;
  	expr->operands[1] = operand2;
  	expr->operator = field_op;
  	expr->name = expr_str(expr, 0);

  	expr->type = kstrdup(operand1->type, GFP_KERNEL);
  	if (!expr->type) {
  		ret = -ENOMEM;
  		goto free;
  	}

  
  	switch (field_op) {
  	case FIELD_OP_MINUS:
  		expr->fn = hist_field_minus;
  		break;
  	case FIELD_OP_PLUS:
  		expr->fn = hist_field_plus;
  		break;
  	default:

  		ret = -EINVAL;

  		goto free;
  	}
  
  	return expr;
   free:
  	destroy_hist_field(operand1, 0);
  	destroy_hist_field(operand2, 0);
  	destroy_hist_field(expr, 0);
  
  	return ERR_PTR(ret);
  }

  static char *find_trigger_filter(struct hist_trigger_data *hist_data,
  				 struct trace_event_file *file)
  {
  	struct event_trigger_data *test;

  	lockdep_assert_held(&event_mutex);
  
  	list_for_each_entry(test, &file->triggers, list) {

  		if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
  			if (test->private_data == hist_data)
  				return test->filter_str;
  		}
  	}
  
  	return NULL;
  }
  
  static struct event_command trigger_hist_cmd;
  static int event_hist_trigger_func(struct event_command *cmd_ops,
  				   struct trace_event_file *file,
  				   char *glob, char *cmd, char *param);
  
  static bool compatible_keys(struct hist_trigger_data *target_hist_data,
  			    struct hist_trigger_data *hist_data,
  			    unsigned int n_keys)
  {
  	struct hist_field *target_hist_field, *hist_field;
  	unsigned int n, i, j;
  
  	if (hist_data->n_fields - hist_data->n_vals != n_keys)
  		return false;
  
  	i = hist_data->n_vals;
  	j = target_hist_data->n_vals;
  
  	for (n = 0; n < n_keys; n++) {
  		hist_field = hist_data->fields[i + n];
  		target_hist_field = target_hist_data->fields[j + n];
  
  		if (strcmp(hist_field->type, target_hist_field->type) != 0)
  			return false;
  		if (hist_field->size != target_hist_field->size)
  			return false;
  		if (hist_field->is_signed != target_hist_field->is_signed)
  			return false;
  	}
  
  	return true;
  }
  
  static struct hist_trigger_data *
  find_compatible_hist(struct hist_trigger_data *target_hist_data,
  		     struct trace_event_file *file)
  {
  	struct hist_trigger_data *hist_data;
  	struct event_trigger_data *test;
  	unsigned int n_keys;

  	lockdep_assert_held(&event_mutex);

  	n_keys = target_hist_data->n_fields - target_hist_data->n_vals;

  	list_for_each_entry(test, &file->triggers, list) {

  		if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
  			hist_data = test->private_data;
  
  			if (compatible_keys(target_hist_data, hist_data, n_keys))
  				return hist_data;
  		}
  	}
  
  	return NULL;
  }
  
  static struct trace_event_file *event_file(struct trace_array *tr,
  					   char *system, char *event_name)
  {
  	struct trace_event_file *file;

  	file = __find_event_file(tr, system, event_name);

  	if (!file)
  		return ERR_PTR(-EINVAL);
  
  	return file;
  }
  
  static struct hist_field *
  find_synthetic_field_var(struct hist_trigger_data *target_hist_data,
  			 char *system, char *event_name, char *field_name)
  {
  	struct hist_field *event_var;
  	char *synthetic_name;
  
  	synthetic_name = kzalloc(MAX_FILTER_STR_VAL, GFP_KERNEL);
  	if (!synthetic_name)
  		return ERR_PTR(-ENOMEM);
  
  	strcpy(synthetic_name, "synthetic_");
  	strcat(synthetic_name, field_name);
  
  	event_var = find_event_var(target_hist_data, system, event_name, synthetic_name);
  
  	kfree(synthetic_name);
  
  	return event_var;
  }
  
  /**
   * create_field_var_hist - Automatically create a histogram and var for a field
   * @target_hist_data: The target hist trigger
   * @subsys_name: Optional subsystem name
   * @event_name: Optional event name
   * @field_name: The name of the field (and the resulting variable)
   *
   * Hist trigger actions fetch data from variables, not directly from
   * events.  However, for convenience, users are allowed to directly
   * specify an event field in an action, which will be automatically
   * converted into a variable on their behalf.
  
   * If a user specifies a field on an event that isn't the event the
   * histogram currently being defined (the target event histogram), the
   * only way that can be accomplished is if a new hist trigger is
   * created and the field variable defined on that.
   *
   * This function creates a new histogram compatible with the target
   * event (meaning a histogram with the same key as the target
   * histogram), and creates a variable for the specified field, but
   * with 'synthetic_' prepended to the variable name in order to avoid
   * collision with normal field variables.
   *
   * Return: The variable created for the field.
   */

  static struct hist_field *

  create_field_var_hist(struct hist_trigger_data *target_hist_data,
  		      char *subsys_name, char *event_name, char *field_name)
  {
  	struct trace_array *tr = target_hist_data->event_file->tr;
  	struct hist_field *event_var = ERR_PTR(-EINVAL);
  	struct hist_trigger_data *hist_data;
  	unsigned int i, n, first = true;
  	struct field_var_hist *var_hist;
  	struct trace_event_file *file;
  	struct hist_field *key_field;
  	char *saved_filter;
  	char *cmd;
  	int ret;

  	if (target_hist_data->n_field_var_hists >= SYNTH_FIELDS_MAX) {

  		hist_err(tr, HIST_ERR_TOO_MANY_FIELD_VARS, errpos(field_name));

  		return ERR_PTR(-EINVAL);

  	}

  
  	file = event_file(tr, subsys_name, event_name);
  
  	if (IS_ERR(file)) {

  		hist_err(tr, HIST_ERR_EVENT_FILE_NOT_FOUND, errpos(field_name));

  		ret = PTR_ERR(file);
  		return ERR_PTR(ret);
  	}
  
  	/*
  	 * Look for a histogram compatible with target.  We'll use the
  	 * found histogram specification to create a new matching
  	 * histogram with our variable on it.  target_hist_data is not
  	 * yet a registered histogram so we can't use that.
  	 */
  	hist_data = find_compatible_hist(target_hist_data, file);

  	if (!hist_data) {

  		hist_err(tr, HIST_ERR_HIST_NOT_FOUND, errpos(field_name));

  		return ERR_PTR(-EINVAL);

  	}

  
  	/* See if a synthetic field variable has already been created */
  	event_var = find_synthetic_field_var(target_hist_data, subsys_name,
  					     event_name, field_name);
  	if (!IS_ERR_OR_NULL(event_var))
  		return event_var;
  
  	var_hist = kzalloc(sizeof(*var_hist), GFP_KERNEL);
  	if (!var_hist)
  		return ERR_PTR(-ENOMEM);
  
  	cmd = kzalloc(MAX_FILTER_STR_VAL, GFP_KERNEL);
  	if (!cmd) {
  		kfree(var_hist);
  		return ERR_PTR(-ENOMEM);
  	}
  
  	/* Use the same keys as the compatible histogram */
  	strcat(cmd, "keys=");
  
  	for_each_hist_key_field(i, hist_data) {
  		key_field = hist_data->fields[i];
  		if (!first)
  			strcat(cmd, ",");
  		strcat(cmd, key_field->field->name);
  		first = false;
  	}
  
  	/* Create the synthetic field variable specification */
  	strcat(cmd, ":synthetic_");
  	strcat(cmd, field_name);
  	strcat(cmd, "=");
  	strcat(cmd, field_name);
  
  	/* Use the same filter as the compatible histogram */
  	saved_filter = find_trigger_filter(hist_data, file);
  	if (saved_filter) {
  		strcat(cmd, " if ");
  		strcat(cmd, saved_filter);
  	}
  
  	var_hist->cmd = kstrdup(cmd, GFP_KERNEL);
  	if (!var_hist->cmd) {
  		kfree(cmd);
  		kfree(var_hist);
  		return ERR_PTR(-ENOMEM);
  	}
  
  	/* Save the compatible histogram information */
  	var_hist->hist_data = hist_data;
  
  	/* Create the new histogram with our variable */
  	ret = event_hist_trigger_func(&trigger_hist_cmd, file,
  				      "", "hist", cmd);
  	if (ret) {
  		kfree(cmd);
  		kfree(var_hist->cmd);
  		kfree(var_hist);

  		hist_err(tr, HIST_ERR_HIST_CREATE_FAIL, errpos(field_name));

  		return ERR_PTR(ret);
  	}
  
  	kfree(cmd);
  
  	/* If we can't find the variable, something went wrong */
  	event_var = find_synthetic_field_var(target_hist_data, subsys_name,
  					     event_name, field_name);
  	if (IS_ERR_OR_NULL(event_var)) {
  		kfree(var_hist->cmd);
  		kfree(var_hist);

  		hist_err(tr, HIST_ERR_SYNTH_VAR_NOT_FOUND, errpos(field_name));

  		return ERR_PTR(-EINVAL);
  	}
  
  	n = target_hist_data->n_field_var_hists;
  	target_hist_data->field_var_hists[n] = var_hist;
  	target_hist_data->n_field_var_hists++;
  
  	return event_var;
  }

  static struct hist_field *

  find_target_event_var(struct hist_trigger_data *hist_data,
  		      char *subsys_name, char *event_name, char *var_name)
  {
  	struct trace_event_file *file = hist_data->event_file;
  	struct hist_field *hist_field = NULL;
  
  	if (subsys_name) {
  		struct trace_event_call *call;
  
  		if (!event_name)
  			return NULL;
  
  		call = file->event_call;
  
  		if (strcmp(subsys_name, call->class->system) != 0)
  			return NULL;
  
  		if (strcmp(event_name, trace_event_name(call)) != 0)
  			return NULL;
  	}
  
  	hist_field = find_var_field(hist_data, var_name);
  
  	return hist_field;
  }
  
  static inline void __update_field_vars(struct tracing_map_elt *elt,
  				       struct ring_buffer_event *rbe,
  				       void *rec,
  				       struct field_var **field_vars,
  				       unsigned int n_field_vars,
  				       unsigned int field_var_str_start)
  {
  	struct hist_elt_data *elt_data = elt->private_data;
  	unsigned int i, j, var_idx;
  	u64 var_val;
  
  	for (i = 0, j = field_var_str_start; i < n_field_vars; i++) {
  		struct field_var *field_var = field_vars[i];
  		struct hist_field *var = field_var->var;
  		struct hist_field *val = field_var->val;
  
  		var_val = val->fn(val, elt, rbe, rec);
  		var_idx = var->var.idx;
  
  		if (val->flags & HIST_FIELD_FL_STRING) {
  			char *str = elt_data->field_var_str[j++];
  			char *val_str = (char *)(uintptr_t)var_val;

  			strscpy(str, val_str, STR_VAR_LEN_MAX);

  			var_val = (u64)(uintptr_t)str;
  		}
  		tracing_map_set_var(elt, var_idx, var_val);
  	}
  }
  
  static void update_field_vars(struct hist_trigger_data *hist_data,
  			      struct tracing_map_elt *elt,
  			      struct ring_buffer_event *rbe,
  			      void *rec)
  {
  	__update_field_vars(elt, rbe, rec, hist_data->field_vars,
  			    hist_data->n_field_vars, 0);
  }

  static void save_track_data_vars(struct hist_trigger_data *hist_data,
  				 struct tracing_map_elt *elt, void *rec,
  				 struct ring_buffer_event *rbe, void *key,
  				 struct action_data *data, u64 *var_ref_vals)

  {

  	__update_field_vars(elt, rbe, rec, hist_data->save_vars,
  			    hist_data->n_save_vars, hist_data->n_field_var_str);

  }

  static struct hist_field *create_var(struct hist_trigger_data *hist_data,
  				     struct trace_event_file *file,
  				     char *name, int size, const char *type)
  {
  	struct hist_field *var;
  	int idx;
  
  	if (find_var(hist_data, file, name) && !hist_data->remove) {
  		var = ERR_PTR(-EINVAL);
  		goto out;
  	}
  
  	var = kzalloc(sizeof(struct hist_field), GFP_KERNEL);
  	if (!var) {
  		var = ERR_PTR(-ENOMEM);
  		goto out;
  	}
  
  	idx = tracing_map_add_var(hist_data->map);
  	if (idx < 0) {
  		kfree(var);
  		var = ERR_PTR(-EINVAL);
  		goto out;
  	}

  	var->ref = 1;

  	var->flags = HIST_FIELD_FL_VAR;
  	var->var.idx = idx;
  	var->var.hist_data = var->hist_data = hist_data;
  	var->size = size;
  	var->var.name = kstrdup(name, GFP_KERNEL);
  	var->type = kstrdup(type, GFP_KERNEL);
  	if (!var->var.name || !var->type) {
  		kfree(var->var.name);
  		kfree(var->type);
  		kfree(var);
  		var = ERR_PTR(-ENOMEM);
  	}
   out:
  	return var;
  }
  
  static struct field_var *create_field_var(struct hist_trigger_data *hist_data,
  					  struct trace_event_file *file,
  					  char *field_name)
  {
  	struct hist_field *val = NULL, *var = NULL;
  	unsigned long flags = HIST_FIELD_FL_VAR;

  	struct trace_array *tr = file->tr;

  	struct field_var *field_var;
  	int ret = 0;
  
  	if (hist_data->n_field_vars >= SYNTH_FIELDS_MAX) {

  		hist_err(tr, HIST_ERR_TOO_MANY_FIELD_VARS, errpos(field_name));

  		ret = -EINVAL;
  		goto err;
  	}
  
  	val = parse_atom(hist_data, file, field_name, &flags, NULL);
  	if (IS_ERR(val)) {

  		hist_err(tr, HIST_ERR_FIELD_VAR_PARSE_FAIL, errpos(field_name));

  		ret = PTR_ERR(val);
  		goto err;
  	}
  
  	var = create_var(hist_data, file, field_name, val->size, val->type);
  	if (IS_ERR(var)) {

  		hist_err(tr, HIST_ERR_VAR_CREATE_FIND_FAIL, errpos(field_name));

  		kfree(val);
  		ret = PTR_ERR(var);
  		goto err;
  	}
  
  	field_var = kzalloc(sizeof(struct field_var), GFP_KERNEL);
  	if (!field_var) {
  		kfree(val);
  		kfree(var);
  		ret =  -ENOMEM;
  		goto err;
  	}
  
  	field_var->var = var;
  	field_var->val = val;
   out:
  	return field_var;
   err:
  	field_var = ERR_PTR(ret);
  	goto out;
  }
  
  /**
   * create_target_field_var - Automatically create a variable for a field
   * @target_hist_data: The target hist trigger
   * @subsys_name: Optional subsystem name
   * @event_name: Optional event name
   * @var_name: The name of the field (and the resulting variable)
   *
   * Hist trigger actions fetch data from variables, not directly from
   * events.  However, for convenience, users are allowed to directly
   * specify an event field in an action, which will be automatically
   * converted into a variable on their behalf.
  
   * This function creates a field variable with the name var_name on
   * the hist trigger currently being defined on the target event.  If
   * subsys_name and event_name are specified, this function simply
   * verifies that they do in fact match the target event subsystem and
   * event name.
   *
   * Return: The variable created for the field.
   */

  static struct field_var *

  create_target_field_var(struct hist_trigger_data *target_hist_data,
  			char *subsys_name, char *event_name, char *var_name)
  {
  	struct trace_event_file *file = target_hist_data->event_file;
  
  	if (subsys_name) {
  		struct trace_event_call *call;
  
  		if (!event_name)
  			return NULL;
  
  		call = file->event_call;
  
  		if (strcmp(subsys_name, call->class->system) != 0)
  			return NULL;
  
  		if (strcmp(event_name, trace_event_name(call)) != 0)
  			return NULL;
  	}
  
  	return create_field_var(target_hist_data, file, var_name);
  }

  static bool check_track_val_max(u64 track_val, u64 var_val)
  {
  	if (var_val <= track_val)
  		return false;
  
  	return true;
  }

  static bool check_track_val_changed(u64 track_val, u64 var_val)
  {
  	if (var_val == track_val)
  		return false;
  
  	return true;
  }

  static u64 get_track_val(struct hist_trigger_data *hist_data,
  			 struct tracing_map_elt *elt,
  			 struct action_data *data)

  {

  	unsigned int track_var_idx = data->track_data.track_var->var.idx;
  	u64 track_val;
  
  	track_val = tracing_map_read_var(elt, track_var_idx);

  	return track_val;
  }
  
  static void save_track_val(struct hist_trigger_data *hist_data,
  			   struct tracing_map_elt *elt,
  			   struct action_data *data, u64 var_val)
  {
  	unsigned int track_var_idx = data->track_data.track_var->var.idx;
  
  	tracing_map_set_var(elt, track_var_idx, var_val);
  }
  
  static void save_track_data(struct hist_trigger_data *hist_data,
  			    struct tracing_map_elt *elt, void *rec,
  			    struct ring_buffer_event *rbe, void *key,
  			    struct action_data *data, u64 *var_ref_vals)
  {
  	if (data->track_data.save_data)
  		data->track_data.save_data(hist_data, elt, rec, rbe, key, data, var_ref_vals);
  }
  
  static bool check_track_val(struct tracing_map_elt *elt,
  			    struct action_data *data,
  			    u64 var_val)
  {
  	struct hist_trigger_data *hist_data;
  	u64 track_val;
  
  	hist_data = data->track_data.track_var->hist_data;
  	track_val = get_track_val(hist_data, elt, data);
  
  	return data->track_data.check_val(track_val, var_val);
  }

  #ifdef CONFIG_TRACER_SNAPSHOT
  static bool cond_snapshot_update(struct trace_array *tr, void *cond_data)
  {
  	/* called with tr->max_lock held */
  	struct track_data *track_data = tr->cond_snapshot->cond_data;
  	struct hist_elt_data *elt_data, *track_elt_data;
  	struct snapshot_context *context = cond_data;

  	struct action_data *action;

  	u64 track_val;
  
  	if (!track_data)
  		return false;

  	action = track_data->action_data;

  	track_val = get_track_val(track_data->hist_data, context->elt,
  				  track_data->action_data);

  	if (!action->track_data.check_val(track_data->track_val, track_val))
  		return false;

  	track_data->track_val = track_val;
  	memcpy(track_data->key, context->key, track_data->key_len);
  
  	elt_data = context->elt->private_data;
  	track_elt_data = track_data->elt.private_data;
  	if (elt_data->comm)

  		strncpy(track_elt_data->comm, elt_data->comm, TASK_COMM_LEN);

  
  	track_data->updated = true;
  
  	return true;
  }
  
  static void save_track_data_snapshot(struct hist_trigger_data *hist_data,
  				     struct tracing_map_elt *elt, void *rec,
  				     struct ring_buffer_event *rbe, void *key,
  				     struct action_data *data,
  				     u64 *var_ref_vals)
  {
  	struct trace_event_file *file = hist_data->event_file;
  	struct snapshot_context context;
  
  	context.elt = elt;
  	context.key = key;
  
  	tracing_snapshot_cond(file->tr, &context);
  }
  
  static void hist_trigger_print_key(struct seq_file *m,
  				   struct hist_trigger_data *hist_data,
  				   void *key,
  				   struct tracing_map_elt *elt);
  
  static struct action_data *snapshot_action(struct hist_trigger_data *hist_data)
  {
  	unsigned int i;
  
  	if (!hist_data->n_actions)
  		return NULL;
  
  	for (i = 0; i < hist_data->n_actions; i++) {
  		struct action_data *data = hist_data->actions[i];
  
  		if (data->action == ACTION_SNAPSHOT)
  			return data;
  	}
  
  	return NULL;
  }
  
  static void track_data_snapshot_print(struct seq_file *m,
  				      struct hist_trigger_data *hist_data)
  {
  	struct trace_event_file *file = hist_data->event_file;
  	struct track_data *track_data;
  	struct action_data *action;
  
  	track_data = tracing_cond_snapshot_data(file->tr);
  	if (!track_data)
  		return;
  
  	if (!track_data->updated)
  		return;
  
  	action = snapshot_action(hist_data);
  	if (!action)
  		return;
  
  	seq_puts(m, "
  Snapshot taken (see tracing/snapshot).  Details:
  ");
  	seq_printf(m, "\ttriggering value { %s(%s) }: %10llu",
  		   action->handler == HANDLER_ONMAX ? "onmax" : "onchange",
  		   action->track_data.var_str, track_data->track_val);
  
  	seq_puts(m, "\ttriggered by event with key: ");
  	hist_trigger_print_key(m, hist_data, track_data->key, &track_data->elt);
  	seq_putc(m, '
  ');
  }
  #else
  static bool cond_snapshot_update(struct trace_array *tr, void *cond_data)
  {
  	return false;
  }
  static void save_track_data_snapshot(struct hist_trigger_data *hist_data,
  				     struct tracing_map_elt *elt, void *rec,
  				     struct ring_buffer_event *rbe, void *key,
  				     struct action_data *data,
  				     u64 *var_ref_vals) {}
  static void track_data_snapshot_print(struct seq_file *m,
  				      struct hist_trigger_data *hist_data) {}
  #endif /* CONFIG_TRACER_SNAPSHOT */

  static void track_data_print(struct seq_file *m,
  			     struct hist_trigger_data *hist_data,
  			     struct tracing_map_elt *elt,
  			     struct action_data *data)
  {
  	u64 track_val = get_track_val(hist_data, elt, data);
  	unsigned int i, save_var_idx;
  
  	if (data->handler == HANDLER_ONMAX)
  		seq_printf(m, "
  \tmax: %10llu", track_val);

  	else if (data->handler == HANDLER_ONCHANGE)
  		seq_printf(m, "
  \tchanged: %10llu", track_val);

  	if (data->action == ACTION_SNAPSHOT)
  		return;

  	for (i = 0; i < hist_data->n_save_vars; i++) {
  		struct hist_field *save_val = hist_data->save_vars[i]->val;
  		struct hist_field *save_var = hist_data->save_vars[i]->var;

  		u64 val;
  
  		save_var_idx = save_var->var.idx;
  
  		val = tracing_map_read_var(elt, save_var_idx);
  
  		if (save_val->flags & HIST_FIELD_FL_STRING) {
  			seq_printf(m, "  %s: %-32s", save_var->var.name,
  				   (char *)(uintptr_t)(val));
  		} else
  			seq_printf(m, "  %s: %10llu", save_var->var.name, val);
  	}
  }

  static void ontrack_action(struct hist_trigger_data *hist_data,
  			   struct tracing_map_elt *elt, void *rec,
  			   struct ring_buffer_event *rbe, void *key,
  			   struct action_data *data, u64 *var_ref_vals)

  {

  	u64 var_val = var_ref_vals[data->track_data.var_ref->var_ref_idx];

  	if (check_track_val(elt, data, var_val)) {
  		save_track_val(hist_data, elt, data, var_val);
  		save_track_data(hist_data, elt, rec, rbe, key, data, var_ref_vals);
  	}

  }

  static void action_data_destroy(struct action_data *data)

  {
  	unsigned int i;

  	lockdep_assert_held(&event_mutex);

  	kfree(data->action_name);

  
  	for (i = 0; i < data->n_params; i++)
  		kfree(data->params[i]);

  	if (data->synth_event)
  		data->synth_event->ref--;

  	kfree(data->synth_event_name);

  	kfree(data);
  }

  static void track_data_destroy(struct hist_trigger_data *hist_data,
  			       struct action_data *data)

  {

  	struct trace_event_file *file = hist_data->event_file;

  	destroy_hist_field(data->track_data.track_var, 0);

  	if (data->action == ACTION_SNAPSHOT) {
  		struct track_data *track_data;
  
  		track_data = tracing_cond_snapshot_data(file->tr);
  		if (track_data && track_data->hist_data == hist_data) {
  			tracing_snapshot_cond_disable(file->tr);
  			track_data_free(track_data);
  		}
  	}

  	kfree(data->track_data.var_str);

  
  	action_data_destroy(data);
  }

  static int action_create(struct hist_trigger_data *hist_data,
  			 struct action_data *data);

  static int track_data_create(struct hist_trigger_data *hist_data,
  			     struct action_data *data)

  {

  	struct hist_field *var_field, *ref_field, *track_var = NULL;

  	struct trace_event_file *file = hist_data->event_file;

  	struct trace_array *tr = file->tr;

  	char *track_data_var_str;

  	int ret = 0;

  	track_data_var_str = data->track_data.var_str;
  	if (track_data_var_str[0] != '$') {

  		hist_err(tr, HIST_ERR_ONX_NOT_VAR, errpos(track_data_var_str));

  		return -EINVAL;

  	}

  	track_data_var_str++;

  	var_field = find_target_event_var(hist_data, NULL, NULL, track_data_var_str);

  	if (!var_field) {

  		hist_err(tr, HIST_ERR_ONX_VAR_NOT_FOUND, errpos(track_data_var_str));

  		return -EINVAL;

  	}

  	ref_field = create_var_ref(hist_data, var_field, NULL, NULL);

  	if (!ref_field)
  		return -ENOMEM;

  	data->track_data.var_ref = ref_field;

  	if (data->handler == HANDLER_ONMAX)
  		track_var = create_var(hist_data, file, "__max", sizeof(u64), "u64");
  	if (IS_ERR(track_var)) {

  		hist_err(tr, HIST_ERR_ONX_VAR_CREATE_FAIL, 0);

  		ret = PTR_ERR(track_var);

  		goto out;
  	}

  
  	if (data->handler == HANDLER_ONCHANGE)
  		track_var = create_var(hist_data, file, "__change", sizeof(u64), "u64");
  	if (IS_ERR(track_var)) {

  		hist_err(tr, HIST_ERR_ONX_VAR_CREATE_FAIL, 0);

  		ret = PTR_ERR(track_var);
  		goto out;
  	}

  	data->track_data.track_var = track_var;

  	ret = action_create(hist_data, data);

   out:
  	return ret;
  }

  static int parse_action_params(struct trace_array *tr, char *params,
  			       struct action_data *data)

  {
  	char *param, *saved_param;

  	bool first_param = true;

  	int ret = 0;
  
  	while (params) {

  		if (data->n_params >= SYNTH_FIELDS_MAX) {

  			hist_err(tr, HIST_ERR_TOO_MANY_PARAMS, 0);

  			goto out;

  		}

  
  		param = strsep(&params, ",");
  		if (!param) {

  			hist_err(tr, HIST_ERR_PARAM_NOT_FOUND, 0);

  			ret = -EINVAL;
  			goto out;
  		}
  
  		param = strstrip(param);
  		if (strlen(param) < 2) {

  			hist_err(tr, HIST_ERR_INVALID_PARAM, errpos(param));

  			ret = -EINVAL;
  			goto out;
  		}
  
  		saved_param = kstrdup(param, GFP_KERNEL);
  		if (!saved_param) {
  			ret = -ENOMEM;
  			goto out;
  		}

  		if (first_param && data->use_trace_keyword) {
  			data->synth_event_name = saved_param;
  			first_param = false;
  			continue;
  		}
  		first_param = false;

  		data->params[data->n_params++] = saved_param;
  	}
   out:
  	return ret;
  }

  static int action_parse(struct trace_array *tr, char *str, struct action_data *data,

  			enum handler_id handler)
  {
  	char *action_name;
  	int ret = 0;
  
  	strsep(&str, ".");
  	if (!str) {

  		hist_err(tr, HIST_ERR_ACTION_NOT_FOUND, 0);

  		ret = -EINVAL;
  		goto out;
  	}
  
  	action_name = strsep(&str, "(");
  	if (!action_name || !str) {

  		hist_err(tr, HIST_ERR_ACTION_NOT_FOUND, 0);

  		ret = -EINVAL;
  		goto out;
  	}
  
  	if (str_has_prefix(action_name, "save")) {
  		char *params = strsep(&str, ")");
  
  		if (!params) {

  			hist_err(tr, HIST_ERR_NO_SAVE_PARAMS, 0);

  			ret = -EINVAL;
  			goto out;
  		}

  		ret = parse_action_params(tr, params, data);

  		if (ret)
  			goto out;
  
  		if (handler == HANDLER_ONMAX)

  			data->track_data.check_val = check_track_val_max;