diff options
Diffstat (limited to 'kernel/time/tick-broadcast.c')
| -rw-r--r-- | kernel/time/tick-broadcast.c | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c index 771d1e0403..b4843099a8 100644 --- a/kernel/time/tick-broadcast.c +++ b/kernel/time/tick-broadcast.c @@ -1141,6 +1141,7 @@ void tick_broadcast_switch_to_oneshot(void) #ifdef CONFIG_HOTPLUG_CPU void hotplug_cpu__broadcast_tick_pull(int deadcpu) { + struct tick_device *td = this_cpu_ptr(&tick_cpu_device); struct clock_event_device *bc; unsigned long flags; @@ -1148,6 +1149,28 @@ void hotplug_cpu__broadcast_tick_pull(int deadcpu) bc = tick_broadcast_device.evtdev; if (bc && broadcast_needs_cpu(bc, deadcpu)) { + /* + * If the broadcast force bit of the current CPU is set, + * then the current CPU has not yet reprogrammed the local + * timer device to avoid a ping-pong race. See + * ___tick_broadcast_oneshot_control(). + * + * If the broadcast device is hrtimer based then + * programming the broadcast event below does not have any + * effect because the local clockevent device is not + * running and not programmed because the broadcast event + * is not earlier than the pending event of the local clock + * event device. As a consequence all CPUs waiting for a + * broadcast event are stuck forever. + * + * Detect this condition and reprogram the cpu local timer + * device to avoid the starvation. + */ + if (tick_check_broadcast_expired()) { + cpumask_clear_cpu(smp_processor_id(), tick_broadcast_force_mask); + tick_program_event(td->evtdev->next_event, 1); + } + /* This moves the broadcast assignment to this CPU: */ clockevents_program_event(bc, bc->next_event, 1); } |