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author | Thomas Gleixner <tglx@linutronix.de> | 2008-09-06 03:01:45 +0200 |
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committer | Thomas Gleixner <tglx@linutronix.de> | 2008-09-06 07:21:17 +0200 |
commit | 7300711e8c6824fcfbd42a126980ff50439d8dd0 (patch) | |
tree | 20183d1ce4fa8237042644b2a79fbf01471da18d /kernel/time/tick-broadcast.c | |
parent | 7cfb0435330364f90f274a26ecdc5f47f738498c (diff) | |
download | linux-7300711e8c6824fcfbd42a126980ff50439d8dd0.tar.gz linux-7300711e8c6824fcfbd42a126980ff50439d8dd0.tar.bz2 linux-7300711e8c6824fcfbd42a126980ff50439d8dd0.zip |
clockevents: broadcast fixup possible waiters
Until the C1E patches arrived there where no users of periodic broadcast
before switching to oneshot mode. Now we need to trigger a possible
waiter for a periodic broadcast when switching to oneshot mode.
Otherwise we can starve them for ever.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/time/tick-broadcast.c')
-rw-r--r-- | kernel/time/tick-broadcast.c | 37 |
1 files changed, 36 insertions, 1 deletions
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c index 2bc1f046151c..2f5a38294bf9 100644 --- a/kernel/time/tick-broadcast.c +++ b/kernel/time/tick-broadcast.c @@ -491,6 +491,18 @@ static void tick_broadcast_clear_oneshot(int cpu) cpu_clear(cpu, tick_broadcast_oneshot_mask); } +static void tick_broadcast_init_next_event(cpumask_t *mask, ktime_t expires) +{ + struct tick_device *td; + int cpu; + + for_each_cpu_mask_nr(cpu, *mask) { + td = &per_cpu(tick_cpu_device, cpu); + if (td->evtdev) + td->evtdev->next_event = expires; + } +} + /** * tick_broadcast_setup_oneshot - setup the broadcast device */ @@ -498,9 +510,32 @@ void tick_broadcast_setup_oneshot(struct clock_event_device *bc) { /* Set it up only once ! */ if (bc->event_handler != tick_handle_oneshot_broadcast) { + int was_periodic = bc->mode == CLOCK_EVT_MODE_PERIODIC; + int cpu = smp_processor_id(); + cpumask_t mask; + bc->event_handler = tick_handle_oneshot_broadcast; clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT); - bc->next_event.tv64 = KTIME_MAX; + + /* Take the do_timer update */ + tick_do_timer_cpu = cpu; + + /* + * We must be careful here. There might be other CPUs + * waiting for periodic broadcast. We need to set the + * oneshot_mask bits for those and program the + * broadcast device to fire. + */ + mask = tick_broadcast_mask; + cpu_clear(cpu, mask); + cpus_or(tick_broadcast_oneshot_mask, + tick_broadcast_oneshot_mask, mask); + + if (was_periodic && !cpus_empty(mask)) { + tick_broadcast_init_next_event(&mask, tick_next_period); + tick_broadcast_set_event(tick_next_period, 1); + } else + bc->next_event.tv64 = KTIME_MAX; } } |