[PATCH bpf-next v6 04/17] bpf: Convert bpf_selem_unlink to failable
From: Amery Hung <hidden>
Date: 2026-02-05 07:02:15
Also in:
bpf
Subsystem:
bpf [core], bpf [general] (safe dynamic programs and tools), networking [general], the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
To prepare changing both bpf_local_storage_map_bucket::lock and bpf_local_storage::lock to rqspinlock, convert bpf_selem_unlink() to failable. It still always succeeds and returns 0 until the change happens. No functional change. Open code bpf_selem_unlink_storage() in the only caller, bpf_selem_unlink(), since unlink_map and unlink_storage must be done together after all the necessary locks are acquired. For bpf_local_storage_map_free(), ignore the return from bpf_selem_unlink() for now. A later patch will allow it to unlink selems even when failing to acquire locks. Signed-off-by: Amery Hung <redacted> --- include/linux/bpf_local_storage.h | 2 +- kernel/bpf/bpf_cgrp_storage.c | 3 +- kernel/bpf/bpf_inode_storage.c | 4 +- kernel/bpf/bpf_local_storage.c | 71 +++++++++++++++---------------- kernel/bpf/bpf_task_storage.c | 4 +- net/core/bpf_sk_storage.c | 4 +- 6 files changed, 39 insertions(+), 49 deletions(-)
diff --git a/include/linux/bpf_local_storage.h b/include/linux/bpf_local_storage.h
index 709506e982a6..f74e0f7656a1 100644
--- a/include/linux/bpf_local_storage.h
+++ b/include/linux/bpf_local_storage.h@@ -176,7 +176,7 @@ 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); -void bpf_selem_unlink(struct bpf_local_storage_elem *selem, bool reuse_now); +int bpf_selem_unlink(struct bpf_local_storage_elem *selem, bool reuse_now); int bpf_selem_link_map(struct bpf_local_storage_map *smap, struct bpf_local_storage *local_storage,
diff --git a/kernel/bpf/bpf_cgrp_storage.c b/kernel/bpf/bpf_cgrp_storage.c
index 0687a760974a..8fef24fcac68 100644
--- a/kernel/bpf/bpf_cgrp_storage.c
+++ b/kernel/bpf/bpf_cgrp_storage.c@@ -118,8 +118,7 @@ static int cgroup_storage_delete(struct cgroup *cgroup, struct bpf_map *map) if (!sdata) return -ENOENT; - bpf_selem_unlink(SELEM(sdata), false); - return 0; + return bpf_selem_unlink(SELEM(sdata), false); } static long bpf_cgrp_storage_delete_elem(struct bpf_map *map, void *key)
diff --git a/kernel/bpf/bpf_inode_storage.c b/kernel/bpf/bpf_inode_storage.c
index e54cce2b9175..cedc99184dad 100644
--- a/kernel/bpf/bpf_inode_storage.c
+++ b/kernel/bpf/bpf_inode_storage.c@@ -110,9 +110,7 @@ static int inode_storage_delete(struct inode *inode, struct bpf_map *map) if (!sdata) return -ENOENT; - bpf_selem_unlink(SELEM(sdata), false); - - return 0; + return bpf_selem_unlink(SELEM(sdata), false); } static long bpf_fd_inode_storage_delete_elem(struct bpf_map *map, void *key)
diff --git a/kernel/bpf/bpf_local_storage.c b/kernel/bpf/bpf_local_storage.c
index bcf7e7f42d18..5dcdf8e523b4 100644
--- a/kernel/bpf/bpf_local_storage.c
+++ b/kernel/bpf/bpf_local_storage.c@@ -308,33 +308,6 @@ static bool bpf_selem_unlink_storage_nolock(struct bpf_local_storage *local_stor return free_local_storage; } -static void bpf_selem_unlink_storage(struct bpf_local_storage_elem *selem, - bool reuse_now) -{ - struct bpf_local_storage *local_storage; - bool free_local_storage = false; - HLIST_HEAD(selem_free_list); - unsigned long flags; - - if (unlikely(!selem_linked_to_storage_lockless(selem))) - /* selem has already been unlinked from sk */ - return; - - local_storage = rcu_dereference_check(selem->local_storage, - bpf_rcu_lock_held()); - - raw_spin_lock_irqsave(&local_storage->lock, flags); - if (likely(selem_linked_to_storage(selem))) - free_local_storage = bpf_selem_unlink_storage_nolock( - local_storage, selem, &selem_free_list); - raw_spin_unlock_irqrestore(&local_storage->lock, flags); - - bpf_selem_free_list(&selem_free_list, reuse_now); - - if (free_local_storage) - bpf_local_storage_free(local_storage, reuse_now); -} - void bpf_selem_link_storage_nolock(struct bpf_local_storage *local_storage, struct bpf_local_storage_elem *selem) {
@@ -387,19 +360,43 @@ static void bpf_selem_link_map_nolock(struct bpf_local_storage_map_bucket *b, hlist_add_head_rcu(&selem->map_node, &b->list); } -void bpf_selem_unlink(struct bpf_local_storage_elem *selem, bool reuse_now) +int bpf_selem_unlink(struct bpf_local_storage_elem *selem, bool reuse_now) { - int err; + struct bpf_local_storage *local_storage; + bool free_local_storage = false; + HLIST_HEAD(selem_free_list); + unsigned long flags; + int err = 0; - /* Always unlink from map before unlinking from local_storage - * because selem will be freed after successfully unlinked from - * the local_storage. - */ - err = bpf_selem_unlink_map(selem); - if (err) - return; + if (unlikely(!selem_linked_to_storage_lockless(selem))) + /* selem has already been unlinked from sk */ + return 0; + + local_storage = rcu_dereference_check(selem->local_storage, + bpf_rcu_lock_held()); + + raw_spin_lock_irqsave(&local_storage->lock, flags); + if (likely(selem_linked_to_storage(selem))) { + /* Always unlink from map before unlinking from local_storage + * because selem will be freed after successfully unlinked from + * the local_storage. + */ + err = bpf_selem_unlink_map(selem); + if (err) + goto out; + + free_local_storage = bpf_selem_unlink_storage_nolock( + local_storage, selem, &selem_free_list); + } +out: + raw_spin_unlock_irqrestore(&local_storage->lock, flags); - bpf_selem_unlink_storage(selem, reuse_now); + bpf_selem_free_list(&selem_free_list, reuse_now); + + if (free_local_storage) + bpf_local_storage_free(local_storage, reuse_now); + + return err; } void __bpf_local_storage_insert_cache(struct bpf_local_storage *local_storage,
diff --git a/kernel/bpf/bpf_task_storage.c b/kernel/bpf/bpf_task_storage.c
index a1dc1bf0848a..ab902364ac23 100644
--- a/kernel/bpf/bpf_task_storage.c
+++ b/kernel/bpf/bpf_task_storage.c@@ -167,9 +167,7 @@ static int task_storage_delete(struct task_struct *task, struct bpf_map *map, if (!nobusy) return -EBUSY; - bpf_selem_unlink(SELEM(sdata), false); - - return 0; + return bpf_selem_unlink(SELEM(sdata), false); } static long bpf_pid_task_storage_delete_elem(struct bpf_map *map, void *key)
diff --git a/net/core/bpf_sk_storage.c b/net/core/bpf_sk_storage.c
index 0b85d8f2c17e..d7b5c4551997 100644
--- a/net/core/bpf_sk_storage.c
+++ b/net/core/bpf_sk_storage.c@@ -40,9 +40,7 @@ static int bpf_sk_storage_del(struct sock *sk, struct bpf_map *map) if (!sdata) return -ENOENT; - bpf_selem_unlink(SELEM(sdata), false); - - return 0; + return bpf_selem_unlink(SELEM(sdata), false); } /* Called by __sk_destruct() & bpf_sk_storage_clone() */
--
2.47.3