From 9c17bcda991000351cb2373f78be7e4b1c44caa3 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Wed, 3 Sep 2008 21:37:08 +0000 Subject: [PATCH] clockevents: prevent multiple init/shutdown While chasing the C1E/HPET bugreports I went through the clock events code inch by inch and found that the broadcast device can be initialized and shutdown multiple times. Multiple shutdowns are not critical, but useless waste of time. Multiple initializations are simply broken. Another CPU might have the device in use already after the first initialization and the second init could just render it unusable again. Signed-off-by: Thomas Gleixner Signed-off-by: Ingo Molnar --- kernel/time/tick-broadcast.c | 20 +++++++++++++------- 1 file changed, 13 insertions(+), 7 deletions(-) diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c index 3044a88357fa..5744f40b2697 100644 --- a/kernel/time/tick-broadcast.c +++ b/kernel/time/tick-broadcast.c @@ -210,7 +210,7 @@ static void tick_do_broadcast_on_off(void *why) struct clock_event_device *bc, *dev; struct tick_device *td; unsigned long flags, *reason = why; - int cpu; + int cpu, bc_stopped; spin_lock_irqsave(&tick_broadcast_lock, flags); @@ -228,6 +228,8 @@ static void tick_do_broadcast_on_off(void *why) if (!tick_device_is_functional(dev)) goto out; + bc_stopped = cpus_empty(tick_broadcast_mask); + switch (*reason) { case CLOCK_EVT_NOTIFY_BROADCAST_ON: case CLOCK_EVT_NOTIFY_BROADCAST_FORCE: @@ -250,9 +252,10 @@ static void tick_do_broadcast_on_off(void *why) break; } - if (cpus_empty(tick_broadcast_mask)) - clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN); - else { + if (cpus_empty(tick_broadcast_mask)) { + if (!bc_stopped) + clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN); + } else if (bc_stopped) { if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) tick_broadcast_start_periodic(bc); else @@ -501,9 +504,12 @@ static void tick_broadcast_clear_oneshot(int cpu) */ void tick_broadcast_setup_oneshot(struct clock_event_device *bc) { - bc->event_handler = tick_handle_oneshot_broadcast; - clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT); - bc->next_event.tv64 = KTIME_MAX; + /* Set it up only once ! */ + if (bc->event_handler != tick_handle_oneshot_broadcast) { + bc->event_handler = tick_handle_oneshot_broadcast; + clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT); + bc->next_event.tv64 = KTIME_MAX; + } } /* -- 2.20.1