Commit 4fa8d68a authored by Kumar Kartikeya Dwivedi's avatar Kumar Kartikeya Dwivedi Committed by Alexei Starovoitov
Browse files

bpf: Convert hashtab.c to rqspinlock 

Convert hashtab.c from raw_spinlock to rqspinlock, and drop the hashed
per-cpu counter crud from the code base which is no longer necessary.

Closes: https://lore.kernel.org/bpf/675302fd.050a0220.2477f.0004.GAE@google.com
Closes: https://lore.kernel.org/bpf/000000000000b3e63e061eed3f6b@google.com


Signed-off-by: default avatarKumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20250316040541.108729-20-memxor@gmail.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent a6884f6f

kernel/bpf/hashtab.c

+32 −70
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
#include "bpf_lru_list.h"

#include "map_in_map.h"

#include <linux/bpf_mem_alloc.h>

#include <asm/rqspinlock.h>



#define HTAB_CREATE_FLAG_MASK						\

	(BPF_F_NO_PREALLOC | BPF_F_NO_COMMON_LRU | BPF_F_NUMA_NODE |	\
@@ -78,7 +79,7 @@ 
 */

struct bucket {

	struct hlist_nulls_head head;

	raw_spinlock_t raw_lock;

	rqspinlock_t raw_lock;

};



#define HASHTAB_MAP_LOCK_COUNT 8
@@ -104,8 +105,6 @@ struct bpf_htab { 
	u32 n_buckets;	/* number of hash buckets */

	u32 elem_size;	/* size of each element in bytes */

	u32 hashrnd;

	struct lock_class_key lockdep_key;

	int __percpu *map_locked[HASHTAB_MAP_LOCK_COUNT];

};



/* each htab element is struct htab_elem + key + value */
@@ -140,45 +139,26 @@ static void htab_init_buckets(struct bpf_htab *htab) 


	for (i = 0; i < htab->n_buckets; i++) {

		INIT_HLIST_NULLS_HEAD(&htab->buckets[i].head, i);

		raw_spin_lock_init(&htab->buckets[i].raw_lock);

		lockdep_set_class(&htab->buckets[i].raw_lock,

					  &htab->lockdep_key);

		raw_res_spin_lock_init(&htab->buckets[i].raw_lock);

		cond_resched();

	}

}



static inline int htab_lock_bucket(const struct bpf_htab *htab,

				   struct bucket *b, u32 hash,

				   unsigned long *pflags)

static inline int htab_lock_bucket(struct bucket *b, unsigned long *pflags)

{

	unsigned long flags;

	int ret;



	hash = hash & min_t(u32, HASHTAB_MAP_LOCK_MASK, htab->n_buckets - 1);



	preempt_disable();

	local_irq_save(flags);

	if (unlikely(__this_cpu_inc_return(*(htab->map_locked[hash])) != 1)) {

		__this_cpu_dec(*(htab->map_locked[hash]));

		local_irq_restore(flags);

		preempt_enable();

		return -EBUSY;

	}



	raw_spin_lock(&b->raw_lock);

	ret = raw_res_spin_lock_irqsave(&b->raw_lock, flags);

	if (ret)

		return ret;

	*pflags = flags;



	return 0;

}



static inline void htab_unlock_bucket(const struct bpf_htab *htab,

				      struct bucket *b, u32 hash,

				      unsigned long flags)

static inline void htab_unlock_bucket(struct bucket *b, unsigned long flags)

{

	hash = hash & min_t(u32, HASHTAB_MAP_LOCK_MASK, htab->n_buckets - 1);

	raw_spin_unlock(&b->raw_lock);

	__this_cpu_dec(*(htab->map_locked[hash]));

	local_irq_restore(flags);

	preempt_enable();

	raw_res_spin_unlock_irqrestore(&b->raw_lock, flags);

}



static bool htab_lru_map_delete_node(void *arg, struct bpf_lru_node *node);
@@ -483,14 +463,12 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *attr) 
	bool percpu_lru = (attr->map_flags & BPF_F_NO_COMMON_LRU);

	bool prealloc = !(attr->map_flags & BPF_F_NO_PREALLOC);

	struct bpf_htab *htab;

	int err, i;

	int err;



	htab = bpf_map_area_alloc(sizeof(*htab), NUMA_NO_NODE);

	if (!htab)

		return ERR_PTR(-ENOMEM);



	lockdep_register_key(&htab->lockdep_key);



	bpf_map_init_from_attr(&htab->map, attr);



	if (percpu_lru) {
@@ -536,15 +514,6 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *attr) 
	if (!htab->buckets)

		goto free_elem_count;



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

		htab->map_locked[i] = bpf_map_alloc_percpu(&htab->map,

							   sizeof(int),

							   sizeof(int),

							   GFP_USER);

		if (!htab->map_locked[i])

			goto free_map_locked;

	}



	if (htab->map.map_flags & BPF_F_ZERO_SEED)

		htab->hashrnd = 0;

	else
@@ -607,15 +576,12 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *attr) 
free_map_locked:

	if (htab->use_percpu_counter)

		percpu_counter_destroy(&htab->pcount);

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

		free_percpu(htab->map_locked[i]);

	bpf_map_area_free(htab->buckets);

	bpf_mem_alloc_destroy(&htab->pcpu_ma);

	bpf_mem_alloc_destroy(&htab->ma);

free_elem_count:

	bpf_map_free_elem_count(&htab->map);

free_htab:

	lockdep_unregister_key(&htab->lockdep_key);

	bpf_map_area_free(htab);

	return ERR_PTR(err);

}
@@ -820,7 +786,7 @@ static bool htab_lru_map_delete_node(void *arg, struct bpf_lru_node *node) 
	b = __select_bucket(htab, tgt_l->hash);

	head = &b->head;



	ret = htab_lock_bucket(htab, b, tgt_l->hash, &flags);

	ret = htab_lock_bucket(b, &flags);

	if (ret)

		return false;
@@ -831,7 +797,7 @@ static bool htab_lru_map_delete_node(void *arg, struct bpf_lru_node *node) 
			break;

		}



	htab_unlock_bucket(htab, b, tgt_l->hash, flags);

	htab_unlock_bucket(b, flags);



	if (l == tgt_l)

		check_and_free_fields(htab, l);
@@ -1150,7 +1116,7 @@ static long htab_map_update_elem(struct bpf_map *map, void *key, void *value, 
		 */

	}



	ret = htab_lock_bucket(htab, b, hash, &flags);

	ret = htab_lock_bucket(b, &flags);

	if (ret)

		return ret;
@@ -1201,7 +1167,7 @@ static long htab_map_update_elem(struct bpf_map *map, void *key, void *value, 
			check_and_free_fields(htab, l_old);

		}

	}

	htab_unlock_bucket(htab, b, hash, flags);

	htab_unlock_bucket(b, flags);

	if (l_old) {

		if (old_map_ptr)

			map->ops->map_fd_put_ptr(map, old_map_ptr, true);
@@ -1210,7 +1176,7 @@ static long htab_map_update_elem(struct bpf_map *map, void *key, void *value, 
	}

	return 0;

err:

	htab_unlock_bucket(htab, b, hash, flags);

	htab_unlock_bucket(b, flags);

	return ret;

}
@@ -1257,7 +1223,7 @@ static long htab_lru_map_update_elem(struct bpf_map *map, void *key, void *value 
	copy_map_value(&htab->map,

		       l_new->key + round_up(map->key_size, 8), value);



	ret = htab_lock_bucket(htab, b, hash, &flags);

	ret = htab_lock_bucket(b, &flags);

	if (ret)

		goto err_lock_bucket;
@@ -1278,7 +1244,7 @@ static long htab_lru_map_update_elem(struct bpf_map *map, void *key, void *value 
	ret = 0;



err:

	htab_unlock_bucket(htab, b, hash, flags);

	htab_unlock_bucket(b, flags);



err_lock_bucket:

	if (ret)
@@ -1315,7 +1281,7 @@ static long __htab_percpu_map_update_elem(struct bpf_map *map, void *key, 
	b = __select_bucket(htab, hash);

	head = &b->head;



	ret = htab_lock_bucket(htab, b, hash, &flags);

	ret = htab_lock_bucket(b, &flags);

	if (ret)

		return ret;
@@ -1340,7 +1306,7 @@ static long __htab_percpu_map_update_elem(struct bpf_map *map, void *key, 
	}

	ret = 0;

err:

	htab_unlock_bucket(htab, b, hash, flags);

	htab_unlock_bucket(b, flags);

	return ret;

}
@@ -1381,7 +1347,7 @@ static long __htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key, 
			return -ENOMEM;

	}



	ret = htab_lock_bucket(htab, b, hash, &flags);

	ret = htab_lock_bucket(b, &flags);

	if (ret)

		goto err_lock_bucket;
@@ -1405,7 +1371,7 @@ static long __htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key, 
	}

	ret = 0;

err:

	htab_unlock_bucket(htab, b, hash, flags);

	htab_unlock_bucket(b, flags);

err_lock_bucket:

	if (l_new) {

		bpf_map_dec_elem_count(&htab->map);
@@ -1447,7 +1413,7 @@ static long htab_map_delete_elem(struct bpf_map *map, void *key) 
	b = __select_bucket(htab, hash);

	head = &b->head;



	ret = htab_lock_bucket(htab, b, hash, &flags);

	ret = htab_lock_bucket(b, &flags);

	if (ret)

		return ret;
@@ -1457,7 +1423,7 @@ static long htab_map_delete_elem(struct bpf_map *map, void *key) 
	else

		ret = -ENOENT;



	htab_unlock_bucket(htab, b, hash, flags);

	htab_unlock_bucket(b, flags);



	if (l)

		free_htab_elem(htab, l);
@@ -1483,7 +1449,7 @@ static long htab_lru_map_delete_elem(struct bpf_map *map, void *key) 
	b = __select_bucket(htab, hash);

	head = &b->head;



	ret = htab_lock_bucket(htab, b, hash, &flags);

	ret = htab_lock_bucket(b, &flags);

	if (ret)

		return ret;
@@ -1494,7 +1460,7 @@ static long htab_lru_map_delete_elem(struct bpf_map *map, void *key) 
	else

		ret = -ENOENT;



	htab_unlock_bucket(htab, b, hash, flags);

	htab_unlock_bucket(b, flags);

	if (l)

		htab_lru_push_free(htab, l);

	return ret;
@@ -1561,7 +1527,6 @@ static void htab_map_free_timers_and_wq(struct bpf_map *map) 
static void htab_map_free(struct bpf_map *map)

{

	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);

	int i;



	/* bpf_free_used_maps() or close(map_fd) will trigger this map_free callback.

	 * bpf_free_used_maps() is called after bpf prog is no longer executing.
@@ -1586,9 +1551,6 @@ static void htab_map_free(struct bpf_map *map) 
	bpf_mem_alloc_destroy(&htab->ma);

	if (htab->use_percpu_counter)

		percpu_counter_destroy(&htab->pcount);

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

		free_percpu(htab->map_locked[i]);

	lockdep_unregister_key(&htab->lockdep_key);

	bpf_map_area_free(htab);

}
@@ -1631,7 +1593,7 @@ static int __htab_map_lookup_and_delete_elem(struct bpf_map *map, void *key, 
	b = __select_bucket(htab, hash);

	head = &b->head;



	ret = htab_lock_bucket(htab, b, hash, &bflags);

	ret = htab_lock_bucket(b, &bflags);

	if (ret)

		return ret;
@@ -1668,7 +1630,7 @@ static int __htab_map_lookup_and_delete_elem(struct bpf_map *map, void *key, 
	hlist_nulls_del_rcu(&l->hash_node);



out_unlock:

	htab_unlock_bucket(htab, b, hash, bflags);

	htab_unlock_bucket(b, bflags);



	if (l) {

		if (is_lru_map)
@@ -1790,7 +1752,7 @@ __htab_map_lookup_and_delete_batch(struct bpf_map *map, 
	head = &b->head;

	/* do not grab the lock unless need it (bucket_cnt > 0). */

	if (locked) {

		ret = htab_lock_bucket(htab, b, batch, &flags);

		ret = htab_lock_bucket(b, &flags);

		if (ret) {

			rcu_read_unlock();

			bpf_enable_instrumentation();
@@ -1813,7 +1775,7 @@ __htab_map_lookup_and_delete_batch(struct bpf_map *map, 
		/* Note that since bucket_cnt > 0 here, it is implicit

		 * that the locked was grabbed, so release it.

		 */

		htab_unlock_bucket(htab, b, batch, flags);

		htab_unlock_bucket(b, flags);

		rcu_read_unlock();

		bpf_enable_instrumentation();

		goto after_loop;
@@ -1824,7 +1786,7 @@ __htab_map_lookup_and_delete_batch(struct bpf_map *map, 
		/* Note that since bucket_cnt > 0 here, it is implicit

		 * that the locked was grabbed, so release it.

		 */

		htab_unlock_bucket(htab, b, batch, flags);

		htab_unlock_bucket(b, flags);

		rcu_read_unlock();

		bpf_enable_instrumentation();

		kvfree(keys);
@@ -1887,7 +1849,7 @@ __htab_map_lookup_and_delete_batch(struct bpf_map *map, 
		dst_val += value_size;

	}



	htab_unlock_bucket(htab, b, batch, flags);

	htab_unlock_bucket(b, flags);

	locked = false;



	while (node_to_free) {