Commit 8e60e05f authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Thomas Gleixner
Browse files

hrtimers: simplify lockdep handling 



In order to avoid the false positive from lockdep, each per-cpu base->lock has
the separate lock class and migrate_hrtimers() uses double_spin_lock().

This is overcomplicated: except for migrate_hrtimers() we never take 2 locks
at once, and migrate_hrtimers() can use spin_lock_nested().

Signed-off-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 0d180406

include/linux/hrtimer.h

+0 −2
Original line number Diff line number Diff line
@@ -173,7 +173,6 @@ struct hrtimer_clock_base { 
 * struct hrtimer_cpu_base - the per cpu clock bases

 * @lock:		lock protecting the base and associated clock bases

 *			and timers

 * @lock_key:		the lock_class_key for use with lockdep

 * @clock_base:		array of clock bases for this cpu

 * @curr_timer:		the timer which is executing a callback right now

 * @expires_next:	absolute time of the next event which was scheduled
@@ -189,7 +188,6 @@ struct hrtimer_clock_base { 
 */

struct hrtimer_cpu_base {

	spinlock_t			lock;

	struct lock_class_key		lock_key;

	struct hrtimer_clock_base	clock_base[HRTIMER_MAX_CLOCK_BASES];

	struct list_head		cb_pending;

#ifdef CONFIG_HIGH_RES_TIMERS

kernel/hrtimer.c

+4 −5
Original line number Diff line number Diff line
@@ -1424,7 +1424,6 @@ static void __cpuinit init_hrtimers_cpu(int cpu) 
	int i;



	spin_lock_init(&cpu_base->lock);

	lockdep_set_class(&cpu_base->lock, &cpu_base->lock_key);



	for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++)

		cpu_base->clock_base[i].cpu_base = cpu_base;
@@ -1465,16 +1464,16 @@ static void migrate_hrtimers(int cpu) 
	tick_cancel_sched_timer(cpu);



	local_irq_disable();

	double_spin_lock(&new_base->lock, &old_base->lock,

			 smp_processor_id() < cpu);

	spin_lock(&new_base->lock);

	spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);



	for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {

		migrate_hrtimer_list(&old_base->clock_base[i],

				     &new_base->clock_base[i]);

	}



	double_spin_unlock(&new_base->lock, &old_base->lock,

			   smp_processor_id() < cpu);

	spin_unlock(&old_base->lock);

	spin_unlock(&new_base->lock);

	local_irq_enable();

	put_cpu_var(hrtimer_bases);

}

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