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: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20250316040541.108729-20-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index 877298133fdae792772b51a780905a97dcd480a4..5a5adc66b8e22454089aab2b2f61961d832b5d3e 100644 (file)
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -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 @@ free_prealloc:
 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 @@ again_nocopy:
        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 @@ again_nocopy:
                /* 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 @@ again_nocopy:
                /* 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 @@ again_nocopy:
                dst_val += value_size;
        }
 
-       htab_unlock_bucket(htab, b, batch, flags);
+       htab_unlock_bucket(b, flags);
        locked = false;
 
        while (node_to_free) {