Commit-ID: e8bd5814989b994cf1b0cb179e1c777e40c0f02c
Gitweb: https://git.kernel.org/tip/e8bd5814989b994cf1b0cb179e1c777e40c0f02c
Author: Peter Zijlstra <pet...@infradead.org>
AuthorDate: Tue, 23 Apr 2019 22:03:18 +0200
Committer: Ingo Molnar <mi...@kernel.org>
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) <pet...@infradead.org>
Cc: Alexei Starovoitov <a...@kernel.org>
Cc: Daniel Borkmann <dan...@iogearbox.net>
Cc: Davidlohr Bueso <d...@stgolabs.net>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Roman Gushchin <g...@fb.com>
Cc: Steven Rostedt <rost...@goodmis.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Tim Chen <tim.c.c...@linux.intel.com>
Cc: Waiman Long <long...@redhat.com>
Cc: Will Deacon <will.dea...@arm.com>
Cc: huang ying <huang.ying.cari...@gmail.com>
Fixes: 2c2d7329d8af ("tracing/ftrace: use preempt_enable_no_resched_notrace in
ring_buffer_time_stamp()")
Link:
https://lkml.kernel.org/r/20190423200318.gy14...@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mi...@kernel.org>
---
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;
}
