Commit c196bf43 authored by Cong Zhang's avatar Cong Zhang Committed by Jens Axboe
Browse files

blk-mq: Abort suspend when wakeup events are pending 



During system suspend, wakeup capable IRQs for block device can be
delayed, which can cause blk_mq_hctx_notify_offline() to hang
indefinitely while waiting for pending request to complete.
Skip the request waiting loop and abort suspend when wakeup events are
pending to prevent the deadlock.

Fixes: bf0beec0 ("blk-mq: drain I/O when all CPUs in a hctx are offline")
Signed-off-by: default avatarCong Zhang <cong.zhang@oss.qualcomm.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 71075d25

block/blk-mq.c

+16 −2
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 
#include <linux/cache.h>

#include <linux/sched/topology.h>

#include <linux/sched/signal.h>

#include <linux/suspend.h>

#include <linux/delay.h>

#include <linux/crash_dump.h>

#include <linux/prefetch.h>
@@ -3718,6 +3719,7 @@ static int blk_mq_hctx_notify_offline(unsigned int cpu, struct hlist_node *node) 
{

	struct blk_mq_hw_ctx *hctx = hlist_entry_safe(node,

			struct blk_mq_hw_ctx, cpuhp_online);

	int ret = 0;



	if (blk_mq_hctx_has_online_cpu(hctx, cpu))

		return 0;
@@ -3738,12 +3740,24 @@ static int blk_mq_hctx_notify_offline(unsigned int cpu, struct hlist_node *node) 
	 * frozen and there are no requests.

	 */

	if (percpu_ref_tryget(&hctx->queue->q_usage_counter)) {

		while (blk_mq_hctx_has_requests(hctx))

		while (blk_mq_hctx_has_requests(hctx)) {

			/*

			 * The wakeup capable IRQ handler of block device is

			 * not called during suspend. Skip the loop by checking

			 * pm_wakeup_pending to prevent the deadlock and improve

			 * suspend latency.

			 */

			if (pm_wakeup_pending()) {

				clear_bit(BLK_MQ_S_INACTIVE, &hctx->state);

				ret = -EBUSY;

				break;

			}

			msleep(5);

		}

		percpu_ref_put(&hctx->queue->q_usage_counter);

	}



	return 0;

	return ret;

}



/*