Add a module refcount, so the current clocksource cannot be removed unconditionally. Signed-off-by: Thomas Gleixner --- include/linux/clocksource.h | 3 +++ kernel/time/timekeeping.c | 15 ++++++++++----- 2 files changed, 13 insertions(+), 5 deletions(-) Index: tip/include/linux/clocksource.h =================================================================== --- tip.orig/include/linux/clocksource.h +++ tip/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 @@ -162,6 +163,7 @@ extern u64 timecounter_cyc2time(struct t * @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 */ struct clocksource { /* @@ -195,6 +197,7 @@ struct clocksource { cycle_t cs_last; cycle_t wd_last; #endif + struct module *owner; } ____cacheline_aligned; /* Index: tip/kernel/time/timekeeping.c =================================================================== --- tip.orig/kernel/time/timekeeping.c +++ tip/kernel/time/timekeeping.c @@ -627,11 +627,16 @@ 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 (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); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/