tracing: Add "uptime" trace clock that uses jiffies

Add a simple trace clock called "uptime" for those that are
interested in the uptime of the trace. It uses jiffies as that's
the safest method, as other uptime clocks grab seq locks, which could
cause a deadlock if taken from an event or function tracer.

Requested-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/trace_clock.h b/include/linux/trace_clock.h
index d563f37e1a1d..1d7ca2739272 100644
--- a/include/linux/trace_clock.h
+++ b/include/linux/trace_clock.h
@@ -16,6 +16,7 @@
 
 extern u64 notrace trace_clock_local(void);
 extern u64 notrace trace_clock(void);
+extern u64 notrace trace_clock_jiffies(void);
 extern u64 notrace trace_clock_global(void);
 extern u64 notrace trace_clock_counter(void);