linux-kernel - Re: WARNING: at block/genhd.c:1556 disk_clear

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Message-ID: <20110415182006.GA15916@mtj.dyndns.org>
Date:	Sat, 16 Apr 2011 03:20:06 +0900
From:	Tejun Heo <tj@...nel.org>
To:	Sitsofe Wheeler <sitsofe@...oo.com>
Cc:	Jens Axboe <axboe@...nel.dk>, linux-kernel@...r.kernel.org
Subject: Re: WARNING: at block/genhd.c:1556 disk_clear_events+0xdc/0xf0()

Please try the following patch instead.  Thanks.

diff --git a/block/genhd.c b/block/genhd.c
index b364bd0..6ed0c17 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1377,6 +1377,8 @@ struct disk_events {
 
 	long			poll_msecs;	/* interval, -1 for default */
 	struct delayed_work	dwork;
+	struct mutex		mutex;
+	atomic_t		cnt;
 };
 
 static const char *disk_events_strs[] = {
@@ -1540,6 +1542,9 @@ unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask)
 		return 0;
 	}
 
+	WARN_ON_ONCE(atomic_add_return(1, &ev->cnt) != 1);
+	mutex_lock(&ev->mutex);
+
 	/* tell the workfn about the events being cleared */
 	spin_lock_irq(&ev->lock);
 	ev->clearing |= mask;
@@ -1558,6 +1563,9 @@ unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask)
 	ev->pending &= ~mask;
 	spin_unlock_irq(&ev->lock);
 
+	WARN_ON_ONCE(atomic_add_return(-1, &ev->cnt) != 0);
+	mutex_unlock(&ev->mutex);
+
 	return pending;
 }
 
@@ -1749,6 +1757,8 @@ static void disk_add_events(struct gendisk *disk)
 	ev->block = 1;
 	ev->poll_msecs = -1;
 	INIT_DELAYED_WORK(&ev->dwork, disk_events_workfn);
+	mutex_init(&ev->mutex);
+	atomic_set(&ev->cnt, 0);
 
 	mutex_lock(&disk_events_mutex);
 	list_add_tail(&ev->node, &disk_events);
--
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