6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yonghong Song <yhs@xxxxxx> [ Upstream commit c83597fa5dc6b322e9bdf929e5f4136a3f4aa4db ] Refactor codes so that inode/task/sk storage implementation can maximally share the same code. I also added some comments in new function bpf_local_storage_unlink_nolock() to make codes easy to understand. There is no functionality change. Acked-by: David Vernet <void@xxxxxxxxxxxxx> Signed-off-by: Yonghong Song <yhs@xxxxxx> Link: https://lore.kernel.org/r/20221026042845.672944-1-yhs@xxxxxx Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx> Stable-dep-of: af253aef183a ("bpf: fix order of args in call to bpf_map_kvcalloc") Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- include/linux/bpf_local_storage.h | 17 ++- kernel/bpf/bpf_inode_storage.c | 38 +----- kernel/bpf/bpf_local_storage.c | 190 +++++++++++++++++++----------- kernel/bpf/bpf_task_storage.c | 38 +----- net/core/bpf_sk_storage.c | 35 +----- 5 files changed, 137 insertions(+), 181 deletions(-) diff --git a/include/linux/bpf_local_storage.h b/include/linux/bpf_local_storage.h index 7ea18d4da84b8..6d37a40cd90e8 100644 --- a/include/linux/bpf_local_storage.h +++ b/include/linux/bpf_local_storage.h @@ -116,21 +116,22 @@ static struct bpf_local_storage_cache name = { \ .idx_lock = __SPIN_LOCK_UNLOCKED(name.idx_lock), \ } -u16 bpf_local_storage_cache_idx_get(struct bpf_local_storage_cache *cache); -void bpf_local_storage_cache_idx_free(struct bpf_local_storage_cache *cache, - u16 idx); - /* Helper functions for bpf_local_storage */ int bpf_local_storage_map_alloc_check(union bpf_attr *attr); -struct bpf_local_storage_map *bpf_local_storage_map_alloc(union bpf_attr *attr); +struct bpf_map * +bpf_local_storage_map_alloc(union bpf_attr *attr, + struct bpf_local_storage_cache *cache); struct bpf_local_storage_data * bpf_local_storage_lookup(struct bpf_local_storage *local_storage, struct bpf_local_storage_map *smap, bool cacheit_lockit); -void bpf_local_storage_map_free(struct bpf_local_storage_map *smap, +bool bpf_local_storage_unlink_nolock(struct bpf_local_storage *local_storage); + +void bpf_local_storage_map_free(struct bpf_map *map, + struct bpf_local_storage_cache *cache, int __percpu *busy_counter); int bpf_local_storage_map_check_btf(const struct bpf_map *map, @@ -141,10 +142,6 @@ int bpf_local_storage_map_check_btf(const struct bpf_map *map, void bpf_selem_link_storage_nolock(struct bpf_local_storage *local_storage, struct bpf_local_storage_elem *selem); -bool bpf_selem_unlink_storage_nolock(struct bpf_local_storage *local_storage, - struct bpf_local_storage_elem *selem, - bool uncharge_omem, bool use_trace_rcu); - void bpf_selem_unlink(struct bpf_local_storage_elem *selem, bool use_trace_rcu); void bpf_selem_link_map(struct bpf_local_storage_map *smap, diff --git a/kernel/bpf/bpf_inode_storage.c b/kernel/bpf/bpf_inode_storage.c index 5f7683b191998..6a1d4d22816a3 100644 --- a/kernel/bpf/bpf_inode_storage.c +++ b/kernel/bpf/bpf_inode_storage.c @@ -56,11 +56,9 @@ static struct bpf_local_storage_data *inode_storage_lookup(struct inode *inode, void bpf_inode_storage_free(struct inode *inode) { - struct bpf_local_storage_elem *selem; struct bpf_local_storage *local_storage; bool free_inode_storage = false; struct bpf_storage_blob *bsb; - struct hlist_node *n; bsb = bpf_inode(inode); if (!bsb) @@ -74,30 +72,11 @@ void bpf_inode_storage_free(struct inode *inode) return; } - /* Neither the bpf_prog nor the bpf-map's syscall - * could be modifying the local_storage->list now. - * Thus, no elem can be added-to or deleted-from the - * local_storage->list by the bpf_prog or by the bpf-map's syscall. - * - * It is racing with bpf_local_storage_map_free() alone - * when unlinking elem from the local_storage->list and - * the map's bucket->list. - */ raw_spin_lock_bh(&local_storage->lock); - hlist_for_each_entry_safe(selem, n, &local_storage->list, snode) { - /* Always unlink from map before unlinking from - * local_storage. - */ - bpf_selem_unlink_map(selem); - free_inode_storage = bpf_selem_unlink_storage_nolock( - local_storage, selem, false, false); - } + free_inode_storage = bpf_local_storage_unlink_nolock(local_storage); raw_spin_unlock_bh(&local_storage->lock); rcu_read_unlock(); - /* free_inoode_storage should always be true as long as - * local_storage->list was non-empty. - */ if (free_inode_storage) kfree_rcu(local_storage, rcu); } @@ -226,23 +205,12 @@ static int notsupp_get_next_key(struct bpf_map *map, void *key, static struct bpf_map *inode_storage_map_alloc(union bpf_attr *attr) { - struct bpf_local_storage_map *smap; - - smap = bpf_local_storage_map_alloc(attr); - if (IS_ERR(smap)) - return ERR_CAST(smap); - - smap->cache_idx = bpf_local_storage_cache_idx_get(&inode_cache); - return &smap->map; + return bpf_local_storage_map_alloc(attr, &inode_cache); } static void inode_storage_map_free(struct bpf_map *map) { - struct bpf_local_storage_map *smap; - - smap = (struct bpf_local_storage_map *)map; - bpf_local_storage_cache_idx_free(&inode_cache, smap->cache_idx); - bpf_local_storage_map_free(smap, NULL); + bpf_local_storage_map_free(map, &inode_cache, NULL); } BTF_ID_LIST_SINGLE(inode_storage_map_btf_ids, struct, diff --git a/kernel/bpf/bpf_local_storage.c b/kernel/bpf/bpf_local_storage.c index d9d88a2cda5e5..b1090a2b02b34 100644 --- a/kernel/bpf/bpf_local_storage.c +++ b/kernel/bpf/bpf_local_storage.c @@ -114,9 +114,9 @@ static void bpf_selem_free_rcu(struct rcu_head *rcu) * The caller must ensure selem->smap is still valid to be * dereferenced for its smap->elem_size and smap->cache_idx. */ -bool bpf_selem_unlink_storage_nolock(struct bpf_local_storage *local_storage, - struct bpf_local_storage_elem *selem, - bool uncharge_mem, bool use_trace_rcu) +static bool bpf_selem_unlink_storage_nolock(struct bpf_local_storage *local_storage, + struct bpf_local_storage_elem *selem, + bool uncharge_mem, bool use_trace_rcu) { struct bpf_local_storage_map *smap; bool free_local_storage; @@ -501,7 +501,7 @@ bpf_local_storage_update(void *owner, struct bpf_local_storage_map *smap, return ERR_PTR(err); } -u16 bpf_local_storage_cache_idx_get(struct bpf_local_storage_cache *cache) +static u16 bpf_local_storage_cache_idx_get(struct bpf_local_storage_cache *cache) { u64 min_usage = U64_MAX; u16 i, res = 0; @@ -525,76 +525,14 @@ u16 bpf_local_storage_cache_idx_get(struct bpf_local_storage_cache *cache) return res; } -void bpf_local_storage_cache_idx_free(struct bpf_local_storage_cache *cache, - u16 idx) +static void bpf_local_storage_cache_idx_free(struct bpf_local_storage_cache *cache, + u16 idx) { spin_lock(&cache->idx_lock); cache->idx_usage_counts[idx]--; spin_unlock(&cache->idx_lock); } -void bpf_local_storage_map_free(struct bpf_local_storage_map *smap, - int __percpu *busy_counter) -{ - struct bpf_local_storage_elem *selem; - struct bpf_local_storage_map_bucket *b; - unsigned int i; - - /* Note that this map might be concurrently cloned from - * bpf_sk_storage_clone. Wait for any existing bpf_sk_storage_clone - * RCU read section to finish before proceeding. New RCU - * read sections should be prevented via bpf_map_inc_not_zero. - */ - synchronize_rcu(); - - /* bpf prog and the userspace can no longer access this map - * now. No new selem (of this map) can be added - * to the owner->storage or to the map bucket's list. - * - * The elem of this map can be cleaned up here - * or when the storage is freed e.g. - * by bpf_sk_storage_free() during __sk_destruct(). - */ - for (i = 0; i < (1U << smap->bucket_log); i++) { - b = &smap->buckets[i]; - - rcu_read_lock(); - /* No one is adding to b->list now */ - while ((selem = hlist_entry_safe( - rcu_dereference_raw(hlist_first_rcu(&b->list)), - struct bpf_local_storage_elem, map_node))) { - if (busy_counter) { - migrate_disable(); - this_cpu_inc(*busy_counter); - } - bpf_selem_unlink(selem, false); - if (busy_counter) { - this_cpu_dec(*busy_counter); - migrate_enable(); - } - cond_resched_rcu(); - } - rcu_read_unlock(); - } - - /* While freeing the storage we may still need to access the map. - * - * e.g. when bpf_sk_storage_free() has unlinked selem from the map - * which then made the above while((selem = ...)) loop - * exit immediately. - * - * However, while freeing the storage one still needs to access the - * smap->elem_size to do the uncharging in - * bpf_selem_unlink_storage_nolock(). - * - * Hence, wait another rcu grace period for the storage to be freed. - */ - synchronize_rcu(); - - kvfree(smap->buckets); - bpf_map_area_free(smap); -} - int bpf_local_storage_map_alloc_check(union bpf_attr *attr) { if (attr->map_flags & ~BPF_LOCAL_STORAGE_CREATE_FLAG_MASK || @@ -614,7 +552,7 @@ int bpf_local_storage_map_alloc_check(union bpf_attr *attr) return 0; } -struct bpf_local_storage_map *bpf_local_storage_map_alloc(union bpf_attr *attr) +static struct bpf_local_storage_map *__bpf_local_storage_map_alloc(union bpf_attr *attr) { struct bpf_local_storage_map *smap; unsigned int i; @@ -664,3 +602,117 @@ int bpf_local_storage_map_check_btf(const struct bpf_map *map, return 0; } + +bool bpf_local_storage_unlink_nolock(struct bpf_local_storage *local_storage) +{ + struct bpf_local_storage_elem *selem; + bool free_storage = false; + struct hlist_node *n; + + /* Neither the bpf_prog nor the bpf_map's syscall + * could be modifying the local_storage->list now. + * Thus, no elem can be added to or deleted from the + * local_storage->list by the bpf_prog or by the bpf_map's syscall. + * + * It is racing with bpf_local_storage_map_free() alone + * when unlinking elem from the local_storage->list and + * the map's bucket->list. + */ + hlist_for_each_entry_safe(selem, n, &local_storage->list, snode) { + /* Always unlink from map before unlinking from + * local_storage. + */ + bpf_selem_unlink_map(selem); + /* If local_storage list has only one element, the + * bpf_selem_unlink_storage_nolock() will return true. + * Otherwise, it will return false. The current loop iteration + * intends to remove all local storage. So the last iteration + * of the loop will set the free_cgroup_storage to true. + */ + free_storage = bpf_selem_unlink_storage_nolock( + local_storage, selem, false, false); + } + + return free_storage; +} + +struct bpf_map * +bpf_local_storage_map_alloc(union bpf_attr *attr, + struct bpf_local_storage_cache *cache) +{ + struct bpf_local_storage_map *smap; + + smap = __bpf_local_storage_map_alloc(attr); + if (IS_ERR(smap)) + return ERR_CAST(smap); + + smap->cache_idx = bpf_local_storage_cache_idx_get(cache); + return &smap->map; +} + +void bpf_local_storage_map_free(struct bpf_map *map, + struct bpf_local_storage_cache *cache, + int __percpu *busy_counter) +{ + struct bpf_local_storage_map_bucket *b; + struct bpf_local_storage_elem *selem; + struct bpf_local_storage_map *smap; + unsigned int i; + + smap = (struct bpf_local_storage_map *)map; + bpf_local_storage_cache_idx_free(cache, smap->cache_idx); + + /* Note that this map might be concurrently cloned from + * bpf_sk_storage_clone. Wait for any existing bpf_sk_storage_clone + * RCU read section to finish before proceeding. New RCU + * read sections should be prevented via bpf_map_inc_not_zero. + */ + synchronize_rcu(); + + /* bpf prog and the userspace can no longer access this map + * now. No new selem (of this map) can be added + * to the owner->storage or to the map bucket's list. + * + * The elem of this map can be cleaned up here + * or when the storage is freed e.g. + * by bpf_sk_storage_free() during __sk_destruct(). + */ + for (i = 0; i < (1U << smap->bucket_log); i++) { + b = &smap->buckets[i]; + + rcu_read_lock(); + /* No one is adding to b->list now */ + while ((selem = hlist_entry_safe( + rcu_dereference_raw(hlist_first_rcu(&b->list)), + struct bpf_local_storage_elem, map_node))) { + if (busy_counter) { + migrate_disable(); + this_cpu_inc(*busy_counter); + } + bpf_selem_unlink(selem, false); + if (busy_counter) { + this_cpu_dec(*busy_counter); + migrate_enable(); + } + cond_resched_rcu(); + } + rcu_read_unlock(); + } + + /* While freeing the storage we may still need to access the map. + * + * e.g. when bpf_sk_storage_free() has unlinked selem from the map + * which then made the above while((selem = ...)) loop + * exit immediately. + * + * However, while freeing the storage one still needs to access the + * smap->elem_size to do the uncharging in + * bpf_selem_unlink_storage_nolock(). + * + * Hence, wait another rcu grace period for the storage to be freed. + */ + synchronize_rcu(); + + kvfree(smap->buckets); + bpf_map_area_free(smap); +} diff --git a/kernel/bpf/bpf_task_storage.c b/kernel/bpf/bpf_task_storage.c index 6f290623347e0..40a92edd6f539 100644 --- a/kernel/bpf/bpf_task_storage.c +++ b/kernel/bpf/bpf_task_storage.c @@ -71,10 +71,8 @@ task_storage_lookup(struct task_struct *task, struct bpf_map *map, void bpf_task_storage_free(struct task_struct *task) { - struct bpf_local_storage_elem *selem; struct bpf_local_storage *local_storage; bool free_task_storage = false; - struct hlist_node *n; unsigned long flags; rcu_read_lock(); @@ -85,32 +83,13 @@ void bpf_task_storage_free(struct task_struct *task) return; } - /* Neither the bpf_prog nor the bpf-map's syscall - * could be modifying the local_storage->list now. - * Thus, no elem can be added-to or deleted-from the - * local_storage->list by the bpf_prog or by the bpf-map's syscall. - * - * It is racing with bpf_local_storage_map_free() alone - * when unlinking elem from the local_storage->list and - * the map's bucket->list. - */ bpf_task_storage_lock(); raw_spin_lock_irqsave(&local_storage->lock, flags); - hlist_for_each_entry_safe(selem, n, &local_storage->list, snode) { - /* Always unlink from map before unlinking from - * local_storage. - */ - bpf_selem_unlink_map(selem); - free_task_storage = bpf_selem_unlink_storage_nolock( - local_storage, selem, false, false); - } + free_task_storage = bpf_local_storage_unlink_nolock(local_storage); raw_spin_unlock_irqrestore(&local_storage->lock, flags); bpf_task_storage_unlock(); rcu_read_unlock(); - /* free_task_storage should always be true as long as - * local_storage->list was non-empty. - */ if (free_task_storage) kfree_rcu(local_storage, rcu); } @@ -288,23 +267,12 @@ static int notsupp_get_next_key(struct bpf_map *map, void *key, void *next_key) static struct bpf_map *task_storage_map_alloc(union bpf_attr *attr) { - struct bpf_local_storage_map *smap; - - smap = bpf_local_storage_map_alloc(attr); - if (IS_ERR(smap)) - return ERR_CAST(smap); - - smap->cache_idx = bpf_local_storage_cache_idx_get(&task_cache); - return &smap->map; + return bpf_local_storage_map_alloc(attr, &task_cache); } static void task_storage_map_free(struct bpf_map *map) { - struct bpf_local_storage_map *smap; - - smap = (struct bpf_local_storage_map *)map; - bpf_local_storage_cache_idx_free(&task_cache, smap->cache_idx); - bpf_local_storage_map_free(smap, &bpf_task_storage_busy); + bpf_local_storage_map_free(map, &task_cache, &bpf_task_storage_busy); } BTF_ID_LIST_SINGLE(task_storage_map_btf_ids, struct, bpf_local_storage_map) diff --git a/net/core/bpf_sk_storage.c b/net/core/bpf_sk_storage.c index ad01b1bea52e4..0124536e8a9db 100644 --- a/net/core/bpf_sk_storage.c +++ b/net/core/bpf_sk_storage.c @@ -48,10 +48,8 @@ static int bpf_sk_storage_del(struct sock *sk, struct bpf_map *map) /* Called by __sk_destruct() & bpf_sk_storage_clone() */ void bpf_sk_storage_free(struct sock *sk) { - struct bpf_local_storage_elem *selem; struct bpf_local_storage *sk_storage; bool free_sk_storage = false; - struct hlist_node *n; rcu_read_lock(); sk_storage = rcu_dereference(sk->sk_bpf_storage); @@ -60,24 +58,8 @@ void bpf_sk_storage_free(struct sock *sk) return; } - /* Netiher the bpf_prog nor the bpf-map's syscall - * could be modifying the sk_storage->list now. - * Thus, no elem can be added-to or deleted-from the - * sk_storage->list by the bpf_prog or by the bpf-map's syscall. - * - * It is racing with bpf_local_storage_map_free() alone - * when unlinking elem from the sk_storage->list and - * the map's bucket->list. - */ raw_spin_lock_bh(&sk_storage->lock); - hlist_for_each_entry_safe(selem, n, &sk_storage->list, snode) { - /* Always unlink from map before unlinking from - * sk_storage. - */ - bpf_selem_unlink_map(selem); - free_sk_storage = bpf_selem_unlink_storage_nolock( - sk_storage, selem, true, false); - } + free_sk_storage = bpf_local_storage_unlink_nolock(sk_storage); raw_spin_unlock_bh(&sk_storage->lock); rcu_read_unlock(); @@ -87,23 +69,12 @@ void bpf_sk_storage_free(struct sock *sk) static void bpf_sk_storage_map_free(struct bpf_map *map) { - struct bpf_local_storage_map *smap; - - smap = (struct bpf_local_storage_map *)map; - bpf_local_storage_cache_idx_free(&sk_cache, smap->cache_idx); - bpf_local_storage_map_free(smap, NULL); + bpf_local_storage_map_free(map, &sk_cache, NULL); } static struct bpf_map *bpf_sk_storage_map_alloc(union bpf_attr *attr) { - struct bpf_local_storage_map *smap; - - smap = bpf_local_storage_map_alloc(attr); - if (IS_ERR(smap)) - return ERR_CAST(smap); - - smap->cache_idx = bpf_local_storage_cache_idx_get(&sk_cache); - return &smap->map; + return bpf_local_storage_map_alloc(attr, &sk_cache); } static int notsupp_get_next_key(struct bpf_map *map, void *key, -- 2.43.0
