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authorOleg Nesterov <oleg@tv-sign.ru>2008-08-20 16:46:04 -0700
committerIngo Molnar <mingo@elte.hu>2008-08-21 13:34:54 +0200
commitd82f0b0f6f1a0a25afc288fb7135b1601fe6df18 (patch)
tree29991ab508ccfbacec6f6b2a7df714ee9d5c5fb5
parent6a55617ed5d1aa62b850de2cf66f5ede2eef4825 (diff)
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migrate_timers: add comment, use spinlock_irq()
Add the comment to explain why the double lock in migrate_timers() can't deadlock. Change the code to use spinlock_irq() instead of local_irq_disable() + spin_lock(). Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Acked-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--kernel/hrtimer.c11
-rw-r--r--kernel/timer.c11
2 files changed, 12 insertions, 10 deletions
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index b8e4dce80a74..03ea1378c43b 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -1620,9 +1620,11 @@ static void migrate_hrtimers(int cpu)
new_base = &get_cpu_var(hrtimer_bases);
tick_cancel_sched_timer(cpu);
-
- local_irq_disable();
- spin_lock(&new_base->lock);
+ /*
+ * The caller is globally serialized and nobody else
+ * takes two locks at once, deadlock is not possible.
+ */
+ spin_lock_irq(&new_base->lock);
spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
@@ -1631,8 +1633,7 @@ static void migrate_hrtimers(int cpu)
}
spin_unlock(&old_base->lock);
- spin_unlock(&new_base->lock);
- local_irq_enable();
+ spin_unlock_irq(&new_base->lock);
put_cpu_var(hrtimer_bases);
}
#endif /* CONFIG_HOTPLUG_CPU */
diff --git a/kernel/timer.c b/kernel/timer.c
index 03bc7f1f1593..e8019cc3418d 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -1435,9 +1435,11 @@ static void __cpuinit migrate_timers(int cpu)
BUG_ON(cpu_online(cpu));
old_base = per_cpu(tvec_bases, cpu);
new_base = get_cpu_var(tvec_bases);
-
- local_irq_disable();
- spin_lock(&new_base->lock);
+ /*
+ * The caller is globally serialized and nobody else
+ * takes two locks at once, deadlock is not possible.
+ */
+ spin_lock_irq(&new_base->lock);
spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
BUG_ON(old_base->running_timer);
@@ -1452,8 +1454,7 @@ static void __cpuinit migrate_timers(int cpu)
}
spin_unlock(&old_base->lock);
- spin_unlock(&new_base->lock);
- local_irq_enable();
+ spin_unlock_irq(&new_base->lock);
put_cpu_var(tvec_bases);
}
#endif /* CONFIG_HOTPLUG_CPU */