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Commit 8dcc3be2 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'trace-fixes-v3.16-rc6' of... 

Merge tag 'trace-fixes-v3.16-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull trace fix from Steven Rostedt:
 "Tony Luck found that using the "uptime" trace clock that uses jiffies
  as a counter was converted to nanoseconds (silly), and after 1 hour 11
  minutes and 34 seconds, this monotonic clock would wrap, causing havoc
  with the tracing system and making the clock useless.

  He converted that clock to use jiffies_64 and made it into a counter
  instead of nanosecond conversions, and displayed the clock with the
  straight jiffy count, which works much better than it did in the past"

* tag 'trace-fixes-v3.16-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Fix wraparound problems in "uptime" trace clock
parents 67dd8f35 58d4e21e

kernel/trace/trace.c

+1 −1
Original line number Diff line number Diff line
@@ -823,7 +823,7 @@ static struct { 
	{ trace_clock_local,	"local",	1 },

	{ trace_clock_global,	"global",	1 },

	{ trace_clock_counter,	"counter",	0 },

	{ trace_clock_jiffies,	"uptime",	1 },

	{ trace_clock_jiffies,	"uptime",	0 },

	{ trace_clock,		"perf",		1 },

	ARCH_TRACE_CLOCKS

};

kernel/trace/trace_clock.c

+5 −4
Original line number Diff line number Diff line
@@ -59,13 +59,14 @@ u64 notrace trace_clock(void) 


/*

 * trace_jiffy_clock(): Simply use jiffies as a clock counter.

 * Note that this use of jiffies_64 is not completely safe on

 * 32-bit systems. But the window is tiny, and the effect if

 * we are affected is that we will have an obviously bogus

 * timestamp on a trace event - i.e. not life threatening.

 */

u64 notrace trace_clock_jiffies(void)

{

	u64 jiffy = jiffies - INITIAL_JIFFIES;



	/* Return nsecs */

	return (u64)jiffies_to_usecs(jiffy) * 1000ULL;

	return jiffies_64_to_clock_t(jiffies_64 - INITIAL_JIFFIES);

}



/*