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tracing: Export tracing clock functions

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Critical tracepoint hooks should never call anything that takes a lock,
so they are unable to call getrawmonotonic() or ktime_get().

Export the rest of the tracing clock functions so can be used in
tracepoint hooks.

Background: We have a customer that adds their own module and registers
a tracepoint hook to sched_wakeup. They were using ktime_get() for a
time source, but it grabs a seq lock and caused a deadlock to occur.

Link: http://lkml.kernel.org/r/1430406624-22609-1-git-send-email-jsnitsel@redhat.com

Signed-off-by: Jerry Snitselaar <jsnitsel@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Jerry Snitselaar 2015-04-30 08:10:24 -07:00 committed by Steven Rostedt
parent 755a27e7e4
commit 7e255d346c
1 changed files with 3 additions and 0 deletions
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3
kernel/trace/trace_clock.c
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@ -56,6 +56,7 @@ u64 notrace trace_clock(void)
{
return local_clock();
}
EXPORT_SYMBOL_GPL(trace_clock);
/*
* trace_jiffy_clock(): Simply use jiffies as a clock counter.
@ -68,6 +69,7 @@ u64 notrace trace_clock_jiffies(void)
{
return jiffies_64_to_clock_t(jiffies_64 - INITIAL_JIFFIES);
}
EXPORT_SYMBOL_GPL(trace_clock_jiffies);
/*
* trace_clock_global(): special globally coherent trace clock
@ -123,6 +125,7 @@ u64 notrace trace_clock_global(void)
return now;
}
EXPORT_SYMBOL_GPL(trace_clock_global);
static atomic64_t trace_counter;