Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
ring-buffer: no preempt for sched_clock()
Impact: disable preemption when calling sched_clock()
The ring_buffer_time_stamp still uses sched_clock as its counter.
But it is a bug to call it with preemption enabled. This requirement
should not be pushed to the ring_buffer_time_stamp callers, so
the ring_buffer_time_stamp needs to disable preemption when calling
sched_clock.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
authored by Steven Rostedt and committed by Ingo Molnar 47e74f2b c1e7abbc
+7
-1
kernel/trace/ring_buffer.c
+7
-1
kernel/trace/ring_buffer.c
···
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/* FIXME!!! */
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u64 ring_buffer_time_stamp(int cpu)
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{
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+
u64 time;
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+
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preempt_disable_notrace();
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/* shift to debug/test normalization and TIME_EXTENTS */
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-
return sched_clock() << DEBUG_SHIFT;
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time = sched_clock() << DEBUG_SHIFT;
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preempt_enable_notrace();
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return time;
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}
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void ring_buffer_normalize_time_stamp(int cpu, u64 *ts)