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lib/fault-inject.c
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#include <linux/kernel.h> #include <linux/init.h> #include <linux/random.h> #include <linux/stat.h> #include <linux/types.h> #include <linux/fs.h> #include <linux/module.h> |
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#include <linux/interrupt.h> |
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#include <linux/unwind.h> #include <linux/stacktrace.h> #include <linux/kallsyms.h> |
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#include <linux/fault-inject.h> /* * setup_fault_attr() is a helper function for various __setup handlers, so it * returns 0 on error, because that is what __setup handlers do. */ int __init setup_fault_attr(struct fault_attr *attr, char *str) { unsigned long probability; unsigned long interval; int times; int space; /* "<interval>,<probability>,<space>,<times>" */ if (sscanf(str, "%lu,%lu,%d,%d", &interval, &probability, &space, ×) < 4) { printk(KERN_WARNING "FAULT_INJECTION: failed to parse arguments "); return 0; } attr->probability = probability; attr->interval = interval; atomic_set(&attr->times, times); atomic_set(&attr->space, space); return 1; } static void fail_dump(struct fault_attr *attr) { if (attr->verbose > 0) printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure "); if (attr->verbose > 1) dump_stack(); } #define atomic_dec_not_zero(v) atomic_add_unless((v), -1, 0) |
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static bool fail_task(struct fault_attr *attr, struct task_struct *task) |
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{ return !in_interrupt() && task->make_it_fail; } |
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#define MAX_STACK_TRACE_DEPTH 32 |
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#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER |
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static bool fail_stacktrace(struct fault_attr *attr) |
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{ struct stack_trace trace; int depth = attr->stacktrace_depth; unsigned long entries[MAX_STACK_TRACE_DEPTH]; int n; bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX); if (depth == 0) return found; trace.nr_entries = 0; trace.entries = entries; |
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trace.max_entries = depth; |
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trace.skip = 1; trace.all_contexts = 0; save_stack_trace(&trace, NULL); for (n = 0; n < trace.nr_entries; n++) { if (attr->reject_start <= entries[n] && entries[n] < attr->reject_end) |
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return false; |
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if (attr->require_start <= entries[n] && entries[n] < attr->require_end) |
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found = true; |
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} return found; } #else |
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static inline bool fail_stacktrace(struct fault_attr *attr) |
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{ |
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return true; |
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} |
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#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ |
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/* * This code is stolen from failmalloc-1.0 * http://www.nongnu.org/failmalloc/ */ |
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bool should_fail(struct fault_attr *attr, ssize_t size) |
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{ |
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if (attr->task_filter && !fail_task(attr, current)) |
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return false; |
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if (atomic_read(&attr->times) == 0) |
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return false; |
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if (atomic_read(&attr->space) > size) { atomic_sub(size, &attr->space); |
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return false; |
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} if (attr->interval > 1) { attr->count++; if (attr->count % attr->interval) |
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return false; |
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} |
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if (attr->probability <= random32() % 100) return false; |
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if (!fail_stacktrace(attr)) return false; |
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fail_dump(attr); if (atomic_read(&attr->times) != -1) atomic_dec_not_zero(&attr->times); |
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return true; |
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} #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS static void debugfs_ul_set(void *data, u64 val) { *(unsigned long *)data = val; } |
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static void debugfs_ul_set_MAX_STACK_TRACE_DEPTH(void *data, u64 val) { *(unsigned long *)data = val < MAX_STACK_TRACE_DEPTH ? val : MAX_STACK_TRACE_DEPTH; } |
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static u64 debugfs_ul_get(void *data) { return *(unsigned long *)data; } DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu "); static struct dentry *debugfs_create_ul(const char *name, mode_t mode, struct dentry *parent, unsigned long *value) { return debugfs_create_file(name, mode, parent, value, &fops_ul); } |
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DEFINE_SIMPLE_ATTRIBUTE(fops_ul_MAX_STACK_TRACE_DEPTH, debugfs_ul_get, debugfs_ul_set_MAX_STACK_TRACE_DEPTH, "%llu "); static struct dentry *debugfs_create_ul_MAX_STACK_TRACE_DEPTH( const char *name, mode_t mode, struct dentry *parent, unsigned long *value) { return debugfs_create_file(name, mode, parent, value, &fops_ul_MAX_STACK_TRACE_DEPTH); } |
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static void debugfs_atomic_t_set(void *data, u64 val) { atomic_set((atomic_t *)data, val); } static u64 debugfs_atomic_t_get(void *data) { return atomic_read((atomic_t *)data); } DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get, debugfs_atomic_t_set, "%lld "); static struct dentry *debugfs_create_atomic_t(const char *name, mode_t mode, struct dentry *parent, atomic_t *value) { return debugfs_create_file(name, mode, parent, value, &fops_atomic_t); } void cleanup_fault_attr_dentries(struct fault_attr *attr) { debugfs_remove(attr->dentries.probability_file); attr->dentries.probability_file = NULL; debugfs_remove(attr->dentries.interval_file); attr->dentries.interval_file = NULL; debugfs_remove(attr->dentries.times_file); attr->dentries.times_file = NULL; debugfs_remove(attr->dentries.space_file); attr->dentries.space_file = NULL; debugfs_remove(attr->dentries.verbose_file); attr->dentries.verbose_file = NULL; |
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debugfs_remove(attr->dentries.task_filter_file); attr->dentries.task_filter_file = NULL; |
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#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER |
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debugfs_remove(attr->dentries.stacktrace_depth_file); attr->dentries.stacktrace_depth_file = NULL; debugfs_remove(attr->dentries.require_start_file); attr->dentries.require_start_file = NULL; debugfs_remove(attr->dentries.require_end_file); attr->dentries.require_end_file = NULL; debugfs_remove(attr->dentries.reject_start_file); attr->dentries.reject_start_file = NULL; debugfs_remove(attr->dentries.reject_end_file); attr->dentries.reject_end_file = NULL; |
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#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ |
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if (attr->dentries.dir) WARN_ON(!simple_empty(attr->dentries.dir)); debugfs_remove(attr->dentries.dir); attr->dentries.dir = NULL; } int init_fault_attr_dentries(struct fault_attr *attr, const char *name) { mode_t mode = S_IFREG | S_IRUSR | S_IWUSR; struct dentry *dir; memset(&attr->dentries, 0, sizeof(attr->dentries)); dir = debugfs_create_dir(name, NULL); if (!dir) goto fail; attr->dentries.dir = dir; attr->dentries.probability_file = debugfs_create_ul("probability", mode, dir, &attr->probability); attr->dentries.interval_file = debugfs_create_ul("interval", mode, dir, &attr->interval); attr->dentries.times_file = debugfs_create_atomic_t("times", mode, dir, &attr->times); attr->dentries.space_file = debugfs_create_atomic_t("space", mode, dir, &attr->space); attr->dentries.verbose_file = debugfs_create_ul("verbose", mode, dir, &attr->verbose); |
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attr->dentries.task_filter_file = debugfs_create_bool("task-filter", mode, dir, &attr->task_filter); |
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if (!attr->dentries.probability_file || !attr->dentries.interval_file || !attr->dentries.times_file || !attr->dentries.space_file || !attr->dentries.verbose_file || !attr->dentries.task_filter_file) goto fail; #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER |
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attr->dentries.stacktrace_depth_file = |
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debugfs_create_ul_MAX_STACK_TRACE_DEPTH( "stacktrace-depth", mode, dir, &attr->stacktrace_depth); |
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attr->dentries.require_start_file = debugfs_create_ul("require-start", mode, dir, &attr->require_start); attr->dentries.require_end_file = debugfs_create_ul("require-end", mode, dir, &attr->require_end); attr->dentries.reject_start_file = debugfs_create_ul("reject-start", mode, dir, &attr->reject_start); attr->dentries.reject_end_file = debugfs_create_ul("reject-end", mode, dir, &attr->reject_end); |
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if (!attr->dentries.stacktrace_depth_file || !attr->dentries.require_start_file || !attr->dentries.require_end_file || !attr->dentries.reject_start_file || !attr->dentries.reject_end_file) |
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goto fail; |
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#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ |
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return 0; fail: cleanup_fault_attr_dentries(attr); return -ENOMEM; } #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */ |