// SPDX-License-Identifier: GPL-2.0-only

  #include <linux/module.h>

  #include <linux/moduleparam.h>

  #include <linux/interval_tree.h>
  #include <linux/random.h>

  #include <linux/slab.h>

  #include <asm/timex.h>

  #define __param(type, name, init, msg)		\
  	static type name = init;		\
  	module_param(name, type, 0444);		\
  	MODULE_PARM_DESC(name, msg);
  
  __param(int, nnodes, 100, "Number of nodes in the interval tree");

  __param(int, perf_loops, 1000, "Number of iterations modifying the tree");

  
  __param(int, nsearches, 100, "Number of searches to the interval tree");

  __param(int, search_loops, 1000, "Number of iterations searching the tree");

  __param(bool, search_all, false, "Searches will iterate all nodes in the tree");

  __param(uint, max_endpoint, ~0, "Largest value for the interval's endpoint");

  static struct rb_root_cached root = RB_ROOT_CACHED;

  static struct interval_tree_node *nodes = NULL;
  static u32 *queries = NULL;

  
  static struct rnd_state rnd;
  
  static inline unsigned long

  search(struct rb_root_cached *root, unsigned long start, unsigned long last)

  {
  	struct interval_tree_node *node;
  	unsigned long results = 0;

  	for (node = interval_tree_iter_first(root, start, last); node;
  	     node = interval_tree_iter_next(node, start, last))

  		results++;
  	return results;
  }
  
  static void init(void)
  {
  	int i;

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

  		u32 b = (prandom_u32_state(&rnd) >> 4) % max_endpoint;
  		u32 a = (prandom_u32_state(&rnd) >> 4) % b;
  
  		nodes[i].start = a;
  		nodes[i].last = b;

  	}

  
  	/*
  	 * Limit the search scope to what the user defined.
  	 * Otherwise we are merely measuring empty walks,
  	 * which is pointless.
  	 */

  	for (i = 0; i < nsearches; i++)

  		queries[i] = (prandom_u32_state(&rnd) >> 4) % max_endpoint;

  }
  
  static int interval_tree_test_init(void)
  {
  	int i, j;
  	unsigned long results;
  	cycles_t time1, time2, time;

  	nodes = kmalloc_array(nnodes, sizeof(struct interval_tree_node),
  			      GFP_KERNEL);

  	if (!nodes)
  		return -ENOMEM;

  	queries = kmalloc_array(nsearches, sizeof(int), GFP_KERNEL);

  	if (!queries) {
  		kfree(nodes);
  		return -ENOMEM;
  	}

  	printk(KERN_ALERT "interval tree insert/remove");

  	prandom_seed_state(&rnd, 3141592653589793238ULL);

  	init();
  
  	time1 = get_cycles();

  	for (i = 0; i < perf_loops; i++) {
  		for (j = 0; j < nnodes; j++)

  			interval_tree_insert(nodes + j, &root);

  		for (j = 0; j < nnodes; j++)

  			interval_tree_remove(nodes + j, &root);
  	}
  
  	time2 = get_cycles();
  	time = time2 - time1;

  	time = div_u64(time, perf_loops);

  	printk(" -> %llu cycles
  ", (unsigned long long)time);
  
  	printk(KERN_ALERT "interval tree search");

  	for (j = 0; j < nnodes; j++)

  		interval_tree_insert(nodes + j, &root);
  
  	time1 = get_cycles();
  
  	results = 0;

  	for (i = 0; i < search_loops; i++)

  		for (j = 0; j < nsearches; j++) {
  			unsigned long start = search_all ? 0 : queries[j];
  			unsigned long last = search_all ? max_endpoint : queries[j];
  
  			results += search(&root, start, last);
  		}

  
  	time2 = get_cycles();
  	time = time2 - time1;

  	time = div_u64(time, search_loops);
  	results = div_u64(results, search_loops);

  	printk(" -> %llu cycles (%lu results)
  ",
  	       (unsigned long long)time, results);

  	kfree(queries);
  	kfree(nodes);

  	return -EAGAIN; /* Fail will directly unload the module */
  }
  
  static void interval_tree_test_exit(void)
  {
  	printk(KERN_ALERT "test exit
  ");
  }
  
  module_init(interval_tree_test_init)
  module_exit(interval_tree_test_exit)
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Michel Lespinasse");
  MODULE_DESCRIPTION("Interval Tree test");