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: bf0beec0607d ("blk-mq: drain I/O when all CPUs in a hctx are offline")
Signed-off-by: Cong Zhang <cong.zhang@oss.qualcomm.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 4e96bb2462475e0dac092066bbf5b976c1611673..bd8b11c472a2537cffac80a5bbdfbc3c2f0884fc 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -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;
 }
 
 /*