diff options
Diffstat (limited to 'kernel/bpf/hashtab.c')
| -rw-r--r-- | kernel/bpf/hashtab.c | 84 |
1 files changed, 73 insertions, 11 deletions
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index fff3650d52fc..570eeca7bdfa 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -26,11 +26,18 @@ struct bpf_htab { struct bucket *buckets; void *elems; struct pcpu_freelist freelist; + void __percpu *extra_elems; atomic_t count; /* number of elements in this hashtable */ u32 n_buckets; /* number of hash buckets */ u32 elem_size; /* size of each element in bytes */ }; +enum extra_elem_state { + HTAB_NOT_AN_EXTRA_ELEM = 0, + HTAB_EXTRA_ELEM_FREE, + HTAB_EXTRA_ELEM_USED +}; + /* each htab element is struct htab_elem + key + value */ struct htab_elem { union { @@ -38,7 +45,10 @@ struct htab_elem { struct bpf_htab *htab; struct pcpu_freelist_node fnode; }; - struct rcu_head rcu; + union { + struct rcu_head rcu; + enum extra_elem_state state; + }; u32 hash; char key[0] __aligned(8); }; @@ -113,6 +123,23 @@ free_elems: return err; } +static int alloc_extra_elems(struct bpf_htab *htab) +{ + void __percpu *pptr; + int cpu; + + pptr = __alloc_percpu_gfp(htab->elem_size, 8, GFP_USER | __GFP_NOWARN); + if (!pptr) + return -ENOMEM; + + for_each_possible_cpu(cpu) { + ((struct htab_elem *)per_cpu_ptr(pptr, cpu))->state = + HTAB_EXTRA_ELEM_FREE; + } + htab->extra_elems = pptr; + return 0; +} + /* Called from syscall */ static struct bpf_map *htab_map_alloc(union bpf_attr *attr) { @@ -185,6 +212,8 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *attr) if (percpu) cost += (u64) round_up(htab->map.value_size, 8) * num_possible_cpus() * htab->map.max_entries; + else + cost += (u64) htab->elem_size * num_possible_cpus(); if (cost >= U32_MAX - PAGE_SIZE) /* make sure page count doesn't overflow */ @@ -212,14 +241,22 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *attr) raw_spin_lock_init(&htab->buckets[i].lock); } + if (!percpu) { + err = alloc_extra_elems(htab); + if (err) + goto free_buckets; + } + if (!(attr->map_flags & BPF_F_NO_PREALLOC)) { err = prealloc_elems_and_freelist(htab); if (err) - goto free_buckets; + goto free_extra_elems; } return &htab->map; +free_extra_elems: + free_percpu(htab->extra_elems); free_buckets: kvfree(htab->buckets); free_htab: @@ -349,7 +386,6 @@ static void htab_elem_free(struct bpf_htab *htab, struct htab_elem *l) if (htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH) free_percpu(htab_elem_get_ptr(l, htab->map.key_size)); kfree(l); - } static void htab_elem_free_rcu(struct rcu_head *head) @@ -370,6 +406,11 @@ static void htab_elem_free_rcu(struct rcu_head *head) static void free_htab_elem(struct bpf_htab *htab, struct htab_elem *l) { + if (l->state == HTAB_EXTRA_ELEM_USED) { + l->state = HTAB_EXTRA_ELEM_FREE; + return; + } + if (!(htab->map.map_flags & BPF_F_NO_PREALLOC)) { pcpu_freelist_push(&htab->freelist, &l->fnode); } else { @@ -381,25 +422,44 @@ static void free_htab_elem(struct bpf_htab *htab, struct htab_elem *l) static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key, void *value, u32 key_size, u32 hash, - bool percpu, bool onallcpus) + bool percpu, bool onallcpus, + bool old_elem_exists) { u32 size = htab->map.value_size; bool prealloc = !(htab->map.map_flags & BPF_F_NO_PREALLOC); struct htab_elem *l_new; void __percpu *pptr; + int err = 0; if (prealloc) { l_new = (struct htab_elem *)pcpu_freelist_pop(&htab->freelist); if (!l_new) - return ERR_PTR(-E2BIG); + err = -E2BIG; } else { if (atomic_inc_return(&htab->count) > htab->map.max_entries) { atomic_dec(&htab->count); - return ERR_PTR(-E2BIG); + err = -E2BIG; + } else { + l_new = kmalloc(htab->elem_size, + GFP_ATOMIC | __GFP_NOWARN); + if (!l_new) + return ERR_PTR(-ENOMEM); } - l_new = kmalloc(htab->elem_size, GFP_ATOMIC | __GFP_NOWARN); - if (!l_new) - return ERR_PTR(-ENOMEM); + } + + if (err) { + if (!old_elem_exists) + return ERR_PTR(err); + + /* if we're updating the existing element and the hash table + * is full, use per-cpu extra elems + */ + l_new = this_cpu_ptr(htab->extra_elems); + if (l_new->state != HTAB_EXTRA_ELEM_FREE) + return ERR_PTR(-E2BIG); + l_new->state = HTAB_EXTRA_ELEM_USED; + } else { + l_new->state = HTAB_NOT_AN_EXTRA_ELEM; } memcpy(l_new->key, key, key_size); @@ -489,7 +549,8 @@ static int htab_map_update_elem(struct bpf_map *map, void *key, void *value, if (ret) goto err; - l_new = alloc_htab_elem(htab, key, value, key_size, hash, false, false); + l_new = alloc_htab_elem(htab, key, value, key_size, hash, false, false, + !!l_old); if (IS_ERR(l_new)) { /* all pre-allocated elements are in use or memory exhausted */ ret = PTR_ERR(l_new); @@ -563,7 +624,7 @@ static int __htab_percpu_map_update_elem(struct bpf_map *map, void *key, } } else { l_new = alloc_htab_elem(htab, key, value, key_size, - hash, true, onallcpus); + hash, true, onallcpus, false); if (IS_ERR(l_new)) { ret = PTR_ERR(l_new); goto err; @@ -652,6 +713,7 @@ static void htab_map_free(struct bpf_map *map) htab_free_elems(htab); pcpu_freelist_destroy(&htab->freelist); } + free_percpu(htab->extra_elems); kvfree(htab->buckets); kfree(htab); } |