| author | Peter Zijlstra <peterz@infradead.org> | 2019-04-23 20:03:18 (GMT) |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-05-02 07:32:00 (GMT) |
| commit | 56f9da8521c004f7acc0cbca2a09dd1894dcffdc (patch) | |
| tree | a7abf7ba0c37c13f17941291c86fd66d157a2641 | |
| parent | 078ffd64d4107605e11ac8f661a59f120061a511 (diff) | |
| download | common-56f9da8521c004f7acc0cbca2a09dd1894dcffdc.zip common-56f9da8521c004f7acc0cbca2a09dd1894dcffdc.tar.gz common-56f9da8521c004f7acc0cbca2a09dd1894dcffdc.tar.bz2 | |
trace: Fix preempt_enable_no_resched() abuse
commit d6097c9e4454adf1f8f2c9547c2fa6060d55d952 upstream.
Unless the very next line is schedule(), or implies it, 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.
Link: http://lkml.kernel.org/r/20190423200318.GY14281@hirez.programming.kicks-ass.net
Cc: Waiman Long <longman@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: the arch/x86 maintainers <x86@kernel.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: huang ying <huang.ying.caritas@gmail.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: stable@vger.kernel.org
Fixes: 2c2d7329d8af ("tracing/ftrace: use preempt_enable_no_resched_notrace in ring_buffer_time_stamp()")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | kernel/trace/ring_buffer.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 5473dca..2cfe11e 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -701,7 +701,7 @@ 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; } |