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Commit f89eae4e authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull scheduler fixes from Ingo Molnar:
 "Two fixes: one for a lost wakeup, the other to fix the compiler
  optimizing out preempt operations on ARM64 (and possibly other non-x86
  architectures)"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/core: Fix remote wakeups
  sched/preempt: Fix preempt_count manipulations
parents bdc6b758 b7e7ade3

include/asm-generic/preempt.h

+2 −2
Original line number Diff line number Diff line
@@ -7,10 +7,10 @@ 


static __always_inline int preempt_count(void)

{

	return current_thread_info()->preempt_count;

	return READ_ONCE(current_thread_info()->preempt_count);

}



static __always_inline int *preempt_count_ptr(void)

static __always_inline volatile int *preempt_count_ptr(void)

{

	return &current_thread_info()->preempt_count;

}

include/linux/sched.h

+1 −0
Original line number Diff line number Diff line
@@ -1539,6 +1539,7 @@ struct task_struct { 
	unsigned sched_reset_on_fork:1;

	unsigned sched_contributes_to_load:1;

	unsigned sched_migrated:1;

	unsigned sched_remote_wakeup:1;

	unsigned :0; /* force alignment to the next boundary */



	/* unserialized, strictly 'current' */

kernel/sched/core.c

+11 −7
Original line number Diff line number Diff line
@@ -1768,13 +1768,15 @@ void sched_ttwu_pending(void) 
	cookie = lockdep_pin_lock(&rq->lock);



	while (llist) {

		int wake_flags = 0;



		p = llist_entry(llist, struct task_struct, wake_entry);

		llist = llist_next(llist);

		/*

		 * See ttwu_queue(); we only call ttwu_queue_remote() when

		 * its a x-cpu wakeup.

		 */

		ttwu_do_activate(rq, p, WF_MIGRATED, cookie);



		if (p->sched_remote_wakeup)

			wake_flags = WF_MIGRATED;



		ttwu_do_activate(rq, p, wake_flags, cookie);

	}



	lockdep_unpin_lock(&rq->lock, cookie);
@@ -1819,10 +1821,12 @@ void scheduler_ipi(void) 
	irq_exit();

}



static void ttwu_queue_remote(struct task_struct *p, int cpu)

static void ttwu_queue_remote(struct task_struct *p, int cpu, int wake_flags)

{

	struct rq *rq = cpu_rq(cpu);



	p->sched_remote_wakeup = !!(wake_flags & WF_MIGRATED);



	if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list)) {

		if (!set_nr_if_polling(rq->idle))

			smp_send_reschedule(cpu);
@@ -1869,7 +1873,7 @@ static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags) 
#if defined(CONFIG_SMP)

	if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) {

		sched_clock_cpu(cpu); /* sync clocks x-cpu */

		ttwu_queue_remote(p, cpu);

		ttwu_queue_remote(p, cpu, wake_flags);

		return;

	}

#endif