diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2013-04-25 20:31:44 +0000 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2013-05-16 11:09:14 +0200 |
| commit | 09ac369c825d9d593404306d59062d854b321e9b (patch) | |
| tree | 0d07679956f56d3203aff526412ec82862083b9a | |
| parent | ba919d1caa2e624eb8c6cae1f2ce0a253e697d45 (diff) | |
clocksource: Add module refcount
Add a module refcount, so the current clocksource cannot be removed
unconditionally.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143435.762417789@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| -rw-r--r-- | include/linux/clocksource.h | 3 | ||||
| -rw-r--r-- | kernel/time/timekeeping.c | 19 |
2 files changed, 17 insertions, 5 deletions
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h index aa6ba44e75d5..32a895b114d8 100644 --- a/include/linux/clocksource.h +++ b/include/linux/clocksource.h @@ -21,6 +21,7 @@ /* clocksource cycle base type */ typedef u64 cycle_t; struct clocksource; +struct module; #ifdef CONFIG_ARCH_CLOCKSOURCE_DATA #include <asm/clocksource.h> @@ -162,6 +163,7 @@ extern u64 timecounter_cyc2time(struct timecounter *tc, * @suspend: suspend function for the clocksource, if necessary * @resume: resume function for the clocksource, if necessary * @cycle_last: most recent cycle counter value seen by ::read() + * @owner: module reference, must be set by clocksource in modules */ struct clocksource { /* @@ -195,6 +197,7 @@ struct clocksource { cycle_t cs_last; cycle_t wd_last; #endif + struct module *owner; } ____cacheline_aligned; /* diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index da6e10c7a378..933efa4071c3 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -627,11 +627,20 @@ static int change_clocksource(void *data) write_seqcount_begin(&timekeeper_seq); timekeeping_forward_now(tk); - if (!new->enable || new->enable(new) == 0) { - old = tk->clock; - tk_setup_internals(tk, new); - if (old->disable) - old->disable(old); + /* + * If the cs is in module, get a module reference. Succeeds + * for built-in code (owner == NULL) as well. + */ + if (try_module_get(new->owner)) { + if (!new->enable || new->enable(new) == 0) { + old = tk->clock; + tk_setup_internals(tk, new); + if (old->disable) + old->disable(old); + module_put(old->owner); + } else { + module_put(new->owner); + } } timekeeping_update(tk, true, true); |