blk-iocost: ioc_pd_free() shouldn't assume irq disabled

ioc_pd_free() grabs irq-safe ioc->lock without ensuring that irq is disabled
when it can be called with irq disabled or enabled. This has a small chance
of causing A-A deadlocks and triggers lockdep splats. Use irqsave operations
instead.

Signed-off-by: Tejun Heo <tj@kernel.org>
Fixes: 7caa471 ("blkcg: implement blk-iocost")
Cc: stable@vger.kernel.org # v5.4+
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-iocost.c

@@ -2092,14 +2092,15 @@ static void ioc_pd_free(struct blkg_policy_data *pd)
 {
 	struct ioc_gq *iocg = pd_to_iocg(pd);
 	struct ioc *ioc = iocg->ioc;
+	unsigned long flags;
 
 	if (ioc) {
-		spin_lock(&ioc->lock);
+		spin_lock_irqsave(&ioc->lock, flags);
 		if (!list_empty(&iocg->active_list)) {
 			propagate_active_weight(iocg, 0, 0);
 			list_del_init(&iocg->active_list);
 		}
-		spin_unlock(&ioc->lock);
+		spin_unlock_irqrestore(&ioc->lock, flags);
 
 		hrtimer_cancel(&iocg->waitq_timer);
 		hrtimer_cancel(&iocg->delay_timer);