From BPF side, preemption usually is enabled. Yonghong said, it is possible that both tasks (at process level) may reach right before "recursion[rctx]++;". In such cases, both tasks will be able to get buffer and this is not right. Signed-off-by: Yonghong Song Signed-off-by: Tao Chen --- kernel/events/internal.h | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/kernel/events/internal.h b/kernel/events/internal.h index d9cc5708309..684bde972ba 100644 --- a/kernel/events/internal.h +++ b/kernel/events/internal.h @@ -214,12 +214,9 @@ static inline int get_recursion_context(u8 *recursion) { unsigned char rctx = interrupt_context_level(); - if (recursion[rctx]) + if (cmpxchg(&recursion[rctx], 0, 1) != 0) return -1; - recursion[rctx]++; - barrier(); - return rctx; } -- 2.48.1