On Sun, 28 Apr 2019 23:39:03 -0700 tip-bot for Peter Zijlstra <tip...@zytor.com> wrote:
> 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 Hi Ingo, I already sent this fix to Linus, and it's been pulled in to his tree. Commit: d6097c9e4454adf1f8f2c9547c2fa6060d55d952 -- Steve > > 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; > }
