[PATCH] fix next_timer_interrupt() for hrtimer
Also from Thomas Gleixner <tglx@linutronix.de>
Function next_timer_interrupt() got broken with a recent patch
6ba1b91213e81aa92b5cf7539f7d2a94ff54947c as sys_nanosleep() was moved to
hrtimer. This broke things as next_timer_interrupt() did not check hrtimer
tree for next event.
Function next_timer_interrupt() is needed with dyntick (CONFIG_NO_IDLE_HZ,
VST) implementations, as the system can be in idle when next hrtimer event
was supposed to happen. At least ARM and S390 currently use
next_timer_interrupt().
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/arm/kernel/time.c b/arch/arm/kernel/time.c
index d7d932c..d6bd435 100644
--- a/arch/arm/kernel/time.c
+++ b/arch/arm/kernel/time.c
@@ -422,12 +422,14 @@
void timer_dyn_reprogram(void)
{
struct dyn_tick_timer *dyn_tick = system_timer->dyn_tick;
+ unsigned long next, seq;
- if (dyn_tick) {
- write_seqlock(&xtime_lock);
- if (dyn_tick->state & DYN_TICK_ENABLED)
+ if (dyn_tick && (dyn_tick->state & DYN_TICK_ENABLED)) {
+ next = next_timer_interrupt();
+ do {
+ seq = read_seqbegin(&xtime_lock);
dyn_tick->reprogram(next_timer_interrupt() - jiffies);
- write_sequnlock(&xtime_lock);
+ } while (read_seqretry(&xtime_lock, seq));
}
}