From: Fernando Luis Vazquez Cao <ferna...@oss.ntt.co.jp>
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").
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Ingo Molnar <mi...@kernel.org>
Cc: Steven Rostedt <rost...@goodmis.org>
Signed-off-by: Fernando Luis Vazquez Cao <ferna...@oss.ntt.co.jp>
---
diff -urNp linux-3.14-rc5-orig/kernel/sched/clock.c
linux-3.14-rc5/kernel/sched/clock.c
--- linux-3.14-rc5-orig/kernel/sched/clock.c 2014-03-06 13:37:43.567720550
+0900
+++ linux-3.14-rc5/kernel/sched/clock.c 2014-03-06 13:41:56.937100949 +0900
@@ -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;
}
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
