Commit-ID: e8bd5814989b994cf1b0cb179e1c777e40c0f02c Gitweb: https://git.kernel.org/tip/e8bd5814989b994cf1b0cb179e1c777e40c0f02c Author: Peter Zijlstra <[email protected]> AuthorDate: Tue, 23 Apr 2019 22:03:18 +0200 Committer: Ingo Molnar <[email protected]> CommitDate: Mon, 29 Apr 2019 08:27:09 +0200
trace: Fix preempt_enable_no_resched() abuse Unless there is a call into schedule() in the immediate (deterministic) future, one must not use preempt_enable_no_resched(). It can cause a preemption to go missing and thereby cause arbitrary delays, breaking the PREEMPT=y invariant. Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Cc: Alexei Starovoitov <[email protected]> Cc: Daniel Borkmann <[email protected]> Cc: Davidlohr Bueso <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Roman Gushchin <[email protected]> Cc: Steven Rostedt <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Tim Chen <[email protected]> Cc: Waiman Long <[email protected]> Cc: Will Deacon <[email protected]> Cc: huang ying <[email protected]> Fixes: 2c2d7329d8af ("tracing/ftrace: use preempt_enable_no_resched_notrace in ring_buffer_time_stamp()") Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- kernel/trace/ring_buffer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 41b6f96e5366..4ee8d8aa3d0f 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -762,7 +762,7 @@ u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu) preempt_disable_notrace(); time = rb_time_stamp(buffer); - preempt_enable_no_resched_notrace(); + preempt_enable_notrace(); return time; }
