[PATCHv2 bpf] bpf,perf: Fix perf_event_detach_bpf_prog error handling

[PATCHv2 bpf] bpf,perf: Fix perf_event_detach_bpf_prog error handling

[Jiri Olsa]

Peter reported that perf_event_detach_bpf_prog might skip to release
the bpf program for -ENOENT error from bpf_prog_array_copy.

This can't happen because bpf program is stored in perf event and is
detached and released only when perf event is freed.

Let's drop the -ENOENT check and make sure the bpf program is released
in any case.

Cc: Sean Young <sean@mess.org>
Fixes: 170a7e3ea070 ("bpf: bpf_prog_array_copy() should return -ENOENT if exclude_prog not found")
Closes: https://lore.kernel.org/lkml/20241022111638.GC16066@noisy.programming.kicks-ass.net/
Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
v2 changes:
- drop the WARN_ON_ONCE check (Andrii, Sean)

 kernel/trace/bpf_trace.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 95b6b3b16bac..630b763e5240 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2216,8 +2216,6 @@ void perf_event_detach_bpf_prog(struct perf_event *event)
 
 	old_array = bpf_event_rcu_dereference(event->tp_event->prog_array);
 	ret = bpf_prog_array_copy(old_array, event->prog, NULL, 0, &new_array);
-	if (ret == -ENOENT)
-		goto unlock;
 	if (ret < 0) {
 		bpf_prog_array_delete_safe(old_array, event->prog);
 	} else {
-- 
2.46.2

Re: [PATCHv2 bpf] bpf,perf: Fix perf_event_detach_bpf_prog error handling

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to bpf/bpf.git (master)
by Andrii Nakryiko <andrii@kernel.org>:

On Wed, 23 Oct 2024 22:03:52 +0200 you wrote:
> Peter reported that perf_event_detach_bpf_prog might skip to release
> the bpf program for -ENOENT error from bpf_prog_array_copy.
> 
> This can't happen because bpf program is stored in perf event and is
> detached and released only when perf event is freed.
> 
> Let's drop the -ENOENT check and make sure the bpf program is released
> in any case.
> 
> [...]

Here is the summary with links:
  - [PATCHv2,bpf] bpf,perf: Fix perf_event_detach_bpf_prog error handling
    https://git.kernel.org/bpf/bpf/c/0ee288e69d03

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html