Commit e0a0d058 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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

Pull cpu hotplug fixes from Thomas Gleixner:
 "Two fixes for the hotplug state machine code:

   - Move the misplaces smb() in the hotplug thread function to the
     proper place, otherwise a half update control struct could be
     observed

   - Prevent state corruption on error rollback, which causes the state
     to advance by one and as a consequence skip it in the bringup
     sequence"

* 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  cpu/hotplug: Prevent state corruption on error rollback
  cpu/hotplug: Adjust misplaced smb() in cpuhp_thread_fun()
parents 3243a89d 69fa6eb7

kernel/cpu.c

+6 −5
Original line number Original line Diff line number Diff line
@@ -607,15 +607,15 @@ static void cpuhp_thread_fun(unsigned int cpu) 
	bool bringup = st->bringup;

	bool bringup = st->bringup;

	enum cpuhp_state state;

	enum cpuhp_state state;





	if (WARN_ON_ONCE(!st->should_run))

		return;



	/*

	/*

	 * ACQUIRE for the cpuhp_should_run() load of ->should_run. Ensures

	 * ACQUIRE for the cpuhp_should_run() load of ->should_run. Ensures

	 * that if we see ->should_run we also see the rest of the state.

	 * that if we see ->should_run we also see the rest of the state.

	 */

	 */

	smp_mb();

	smp_mb();





	if (WARN_ON_ONCE(!st->should_run))

		return;



	cpuhp_lock_acquire(bringup);

	cpuhp_lock_acquire(bringup);





	if (st->single) {

	if (st->single) {
@@ -916,6 +916,7 @@ static int cpuhp_down_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st, 
		ret = cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL);

		ret = cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL);

		if (ret) {

		if (ret) {

			st->target = prev_state;

			st->target = prev_state;

			if (st->state < prev_state)

				undo_cpu_down(cpu, st);

				undo_cpu_down(cpu, st);

			break;

			break;

		}

		}
@@ -969,7 +970,7 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen, 
	 * to do the further cleanups.

	 * to do the further cleanups.

	 */

	 */

	ret = cpuhp_down_callbacks(cpu, st, target);

	ret = cpuhp_down_callbacks(cpu, st, target);

	if (ret && st->state > CPUHP_TEARDOWN_CPU && st->state < prev_state) {

	if (ret && st->state == CPUHP_TEARDOWN_CPU && st->state < prev_state) {

		cpuhp_reset_state(st, prev_state);

		cpuhp_reset_state(st, prev_state);

		__cpuhp_kick_ap(st);

		__cpuhp_kick_ap(st);

	}

	}