[RFC][PATCH 1/2] Remove stop_machine from change_clocksource
in [Kernel]
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From: John Stultz on 27 Jul 2010 22:10 To me, there isn't a clear reason why we're using stop_machine when changing clocksources instead of just taking the xtime_lock. Additionally, using stop_machine limits us from being able to register clocksources from timers (as needed for a following patch). This patch simply removes the stop_machine usage and instead directly calls change_clocksource, which now takes the xtime_lock. I could be totally missing something here that necessitates stop_machine, but in my testing it seems to function fine. Any clarifications or corrections would be appreciated! Signed-off-by: John Stultz <johnstul(a)us.ibm.com> CC: Thomas Gleixner <tglx(a)linutronix.de> CC: Martin Schwidefsky <schwidefsky(a)de.ibm.com> CC: Clark Williams <williams(a)redhat.com> --- kernel/time/timekeeping.c | 12 ++++++------ 1 files changed, 6 insertions(+), 6 deletions(-) diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index e14c839..fa2cc41 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -19,7 +19,6 @@ #include <linux/jiffies.h> #include <linux/time.h> #include <linux/tick.h> -#include <linux/stop_machine.h> /* Structure holding internal timekeeping values. */ struct timekeeper { @@ -345,12 +344,12 @@ EXPORT_SYMBOL(do_settimeofday); * * Accumulates current time interval and initializes new clocksource */ -static int change_clocksource(void *data) +static int change_clocksource(struct clocksource *new) { - struct clocksource *new, *old; - - new = (struct clocksource *) data; + struct clocksource *old; + unsigned long flags; + write_seqlock_irqsave(&xtime_lock, flags); timekeeping_forward_now(); if (!new->enable || new->enable(new) == 0) { old = timekeeper.clock; @@ -358,6 +357,7 @@ static int change_clocksource(void *data) if (old->disable) old->disable(old); } + write_sequnlock_irqrestore(&xtime_lock, flags); return 0; } @@ -372,7 +372,7 @@ void timekeeping_notify(struct clocksource *clock) { if (timekeeper.clock == clock) return; - stop_machine(change_clocksource, clock, NULL); + change_clocksource(clock); tick_clock_notify(); } -- 1.6.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |