* Steven Rostedt ([EMAIL PROTECTED]) wrote: > The latency tracer can call clocksource_read very early in bootup and > before the clock source variable has been initialized. This results in a > crash at boot up (even before earlyprintk is initialized). Since the > clock->read variable points to NULL. > > This patch simply initializes the clock to use clocksource_jiffies, so > that any early user of clocksource_read will not crash. >
Hrm, is it sane at all to use the jiffies as a clocksource at early boot? I thought it was updated by the timer interrupt, which is only activated late in the boot process. > Signed-off-by: Steven Rostedt <[EMAIL PROTECTED]> > Acked-by: John Stultz <[EMAIL PROTECTED]> > --- > include/linux/clocksource.h | 3 +++ > kernel/time/timekeeping.c | 9 +++++++-- > 2 files changed, 10 insertions(+), 2 deletions(-) > > Index: linux-compile.git/include/linux/clocksource.h > =================================================================== > --- linux-compile.git.orig/include/linux/clocksource.h 2008-01-14 > 13:14:14.000000000 -0500 > +++ linux-compile.git/include/linux/clocksource.h 2008-01-14 > 14:57:46.000000000 -0500 > @@ -274,6 +274,9 @@ extern struct clocksource* clocksource_g > extern void clocksource_change_rating(struct clocksource *cs, int rating); > extern void clocksource_resume(void); > > +/* used to initialize clock */ > +extern struct clocksource clocksource_jiffies; > + > #ifdef CONFIG_GENERIC_TIME_VSYSCALL > extern void update_vsyscall(struct timespec *ts, struct clocksource *c); > extern void update_vsyscall_tz(void); > Index: linux-compile.git/kernel/time/timekeeping.c > =================================================================== > --- linux-compile.git.orig/kernel/time/timekeeping.c 2008-01-14 > 13:14:14.000000000 -0500 > +++ linux-compile.git/kernel/time/timekeeping.c 2008-01-14 > 14:57:46.000000000 -0500 > @@ -53,8 +53,13 @@ static inline void update_xtime_cache(u6 > timespec_add_ns(&xtime_cache, nsec); > } > > -static struct clocksource *clock; /* pointer to current clocksource */ > - > +/* > + * pointer to current clocksource > + * Just in case we use clocksource_read before we initialize > + * the actual clock source. Instead of calling a NULL read pointer > + * we return jiffies. > + */ > +static struct clocksource *clock = &clocksource_jiffies; > > #ifdef CONFIG_GENERIC_TIME > /** > > -- -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
