Commit-ID: 96b3d28bf4b00f62fc8386ff5d487d1830793a3d
Gitweb: http://git.kernel.org/tip/96b3d28bf4b00f62fc8386ff5d487d1830793a3d
Author: Fernando Luis Vazquez Cao <fernando@xxxxxxxxxxxxx>
AuthorDate: Thu, 6 Mar 2014 14:25:28 +0900
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Tue, 11 Mar 2014 11:33:48 +0100
sched/clock: Prevent tracing recursion in sched_clock_cpu()
Prevent tracing of preempt_disable/enable() in sched_clock_cpu().
When CONFIG_DEBUG_PREEMPT is enabled, preempt_disable/enable() are
traced and this causes trace_clock() users (and probably others) to
go into an infinite recursion. Systems with a stable sched_clock()
are not affected.
This problem is similar to that fixed by upstream commit 95ef1e52922
("KVM guest: prevent tracing recursion with kvmclock").
Signed-off-by: Fernando Luis Vazquez Cao <fernando@xxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Acked-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1394083528.4524.3.camel@nexus
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/sched/clock.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c
index 43c2bcc..b30a292 100644
--- a/kernel/sched/clock.c
+++ b/kernel/sched/clock.c
@@ -301,14 +301,14 @@ u64 sched_clock_cpu(int cpu)
if (unlikely(!sched_clock_running))
return 0ull;
- preempt_disable();
+ preempt_disable_notrace();
scd = cpu_sdc(cpu);
if (cpu != smp_processor_id())
clock = sched_clock_remote(scd);
else
clock = sched_clock_local(scd);
- preempt_enable();
+ preempt_enable_notrace();
return clock;
}
--
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