diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2014-07-21 22:43:15 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-07-21 22:43:15 -0700 |
| commit | 8dcc3be2a4fdf0560c43ae30a149ac1e4b70495f (patch) | |
| tree | 8de9c6f5800991d6d81408013006c38700cc1ed3 | |
| parent | 67dd8f35c2d8ed80f26c9654b474cffc11c6674d (diff) | |
| parent | 58d4e21e50ff3cc57910a8abc20d7e14375d2f61 (diff) | |
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
| -rw-r--r-- | kernel/trace/trace.c | 2 | ||||
| -rw-r--r-- | kernel/trace/trace_clock.c | 9 |
2 files changed, 6 insertions, 5 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index bda9621638cc..291397e66669 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -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 }; diff --git a/kernel/trace/trace_clock.c b/kernel/trace/trace_clock.c index 26dc348332b7..57b67b1f24d1 100644 --- a/kernel/trace/trace_clock.c +++ b/kernel/trace/trace_clock.c @@ -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); } /* |