diff mbox series

[bpf-next] bpf: no longer acquire map_idr_lock in bpf_map_inc_not_zero()

Message ID 20250301191315.1532629-1-edumazet@google.com (mailing list archive)
State Accepted
Commit 17a82ed98f62e0b3d2465e482ae5d0503e989a48
Delegated to: BPF
Headers show
Series [bpf-next] bpf: no longer acquire map_idr_lock in bpf_map_inc_not_zero() | expand

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Commit Message

Eric Dumazet March 1, 2025, 7:13 p.m. UTC 
bpf_sk_storage_clone() is the only caller of bpf_map_inc_not_zero()
and is holding rcu_read_lock().

map_idr_lock does not add any protection, just remove the cost
for passive TCP flows.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Kui-Feng Lee <kuifeng@meta.com>
Cc: Martin KaFai Lau <martin.lau@kernel.org>
---
 kernel/bpf/syscall.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

Comments

Stanislav Fomichev March 2, 2025, 12:05 a.m. UTC | #1 
On 03/01, Eric Dumazet wrote:
> bpf_sk_storage_clone() is the only caller of bpf_map_inc_not_zero()
> and is holding rcu_read_lock().
> 
> map_idr_lock does not add any protection, just remove the cost
> for passive TCP flows.
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Acked-by: Stanislav Fomichev <sdf@fomichev.me>
patchwork-bot+netdevbpf@kernel.org March 3, 2025, 2:30 a.m. UTC | #2 
Hello:

This patch was applied to bpf/bpf-next.git (master)
by Alexei Starovoitov <ast@kernel.org>:

On Sat,  1 Mar 2025 19:13:15 +0000 you wrote:
> bpf_sk_storage_clone() is the only caller of bpf_map_inc_not_zero()
> and is holding rcu_read_lock().
> 
> map_idr_lock does not add any protection, just remove the cost
> for passive TCP flows.
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Cc: Kui-Feng Lee <kuifeng@meta.com>
> Cc: Martin KaFai Lau <martin.lau@kernel.org>
> 
> [...]

Here is the summary with links:
  - [bpf-next] bpf: no longer acquire map_idr_lock in bpf_map_inc_not_zero()
    https://git.kernel.org/bpf/bpf-next/c/17a82ed98f62

You are awesome, thank you!
diff mbox series

Patch

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index e1e42e918ba7f682223e9a78028bb0cc360c01ce..d68c8d61f7ceddb732a5646c00b8f0c71fdc2d71 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1593,11 +1593,8 @@  struct bpf_map *__bpf_map_inc_not_zero(struct bpf_map *map, bool uref)
 
 struct bpf_map *bpf_map_inc_not_zero(struct bpf_map *map)
 {
-	spin_lock_bh(&map_idr_lock);
-	map = __bpf_map_inc_not_zero(map, false);
-	spin_unlock_bh(&map_idr_lock);
-
-	return map;
+	lockdep_assert(rcu_read_lock_held());
+	return __bpf_map_inc_not_zero(map, false);
 }
 EXPORT_SYMBOL_GPL(bpf_map_inc_not_zero);