From: Christoph Hellwig <hch@lst.de>
To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Jens Axboe <axboe@kernel.dk>, Christoph Hellwig <hch@lst.de>,
Greg KH <gregkh@linuxfoundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Hannes Reinecke <hare@suse.de>,
Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>,
Hillf Danton <hdanton@sina.com>,
Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>,
linux-block <linux-block@vger.kernel.org>
Subject: Re: [PATCH v3] block: genhd: don't call probe function with major_names_lock held
Date: Mon, 16 Aug 2021 09:33:13 +0200 [thread overview]
Message-ID: <20210816073313.GA27275@lst.de> (raw)
In-Reply-To: <4e153910-bf60-2cca-fa02-b46d22b6e2c5@i-love.sakura.ne.jp>
This is the wrong way to approach it. Instead of making things ever
more complex try to make it simpler. In this case, ensure that the
destroy_workqueue is not held with pointless locks. Given that the
loop device already is known to not have a reference and marked as in
the rundown state there shouldn't be anything that is required to
be protected by lo_mutex. So something like this untested patch
should probably do the work:
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index fa1c298a8cfb..c734dc768316 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1347,16 +1347,15 @@ static int __loop_clr_fd(struct loop_device *lo, bool release)
* became visible.
*/
- mutex_lock(&lo->lo_mutex);
if (WARN_ON_ONCE(lo->lo_state != Lo_rundown)) {
err = -ENXIO;
- goto out_unlock;
+ goto out;
}
filp = lo->lo_backing_file;
if (filp == NULL) {
err = -EINVAL;
- goto out_unlock;
+ goto out;
}
if (test_bit(QUEUE_FLAG_WC, &lo->lo_queue->queue_flags))
@@ -1366,6 +1365,8 @@ static int __loop_clr_fd(struct loop_device *lo, bool release)
blk_mq_freeze_queue(lo->lo_queue);
destroy_workqueue(lo->workqueue);
+
+ mutex_lock(&lo->lo_mutex);
spin_lock_irq(&lo->lo_work_lock);
list_for_each_entry_safe(worker, pos, &lo->idle_worker_list,
idle_list) {
@@ -1413,8 +1414,8 @@ static int __loop_clr_fd(struct loop_device *lo, bool release)
partscan = lo->lo_flags & LO_FLAGS_PARTSCAN && bdev;
lo_number = lo->lo_number;
disk_force_media_change(lo->lo_disk, DISK_EVENT_MEDIA_CHANGE);
-out_unlock:
mutex_unlock(&lo->lo_mutex);
+
if (partscan) {
/*
* open_mutex has been held already in release path, so don't
@@ -1435,7 +1436,7 @@ static int __loop_clr_fd(struct loop_device *lo, bool release)
/* Device is gone, no point in returning error */
err = 0;
}
-
+out:
/*
* lo->lo_state is set to Lo_unbound here after above partscan has
* finished.
next prev parent reply other threads:[~2021-08-16 7:33 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-19 1:05 [PATCH v2] block: genhd: don't call probe function with major_names_lock held Tetsuo Handa
2021-06-19 3:24 ` kernel test robot
2021-06-19 6:14 ` kernel test robot
2021-06-19 6:44 ` Greg KH
2021-06-19 8:47 ` Tetsuo Handa
[not found] ` <20210620024403.820-1-hdanton@sina.com>
2021-06-20 13:54 ` Tetsuo Handa
2021-06-21 8:54 ` Greg KH
2021-06-21 6:18 ` Christoph Hellwig
2021-08-15 6:52 ` [PATCH v3] " Tetsuo Handa
2021-08-15 7:06 ` Greg KH
2021-08-15 7:49 ` Tetsuo Handa
2021-08-15 9:19 ` Greg KH
2021-08-18 11:07 ` [PATCH v4] " Tetsuo Handa
2021-08-18 13:27 ` Greg KH
2021-08-18 14:44 ` Tetsuo Handa
2021-08-18 15:28 ` Greg KH
2021-08-21 6:12 ` [PATCH v5] " Tetsuo Handa
2021-08-18 13:47 ` [PATCH v4] " Christoph Hellwig
2021-08-18 14:34 ` Tetsuo Handa
2021-08-18 14:41 ` Greg KH
2021-08-18 14:51 ` Tetsuo Handa
2021-08-19 9:16 ` Christoph Hellwig
2021-08-19 14:47 ` Tetsuo Handa
2021-08-19 9:19 ` Christoph Hellwig
2021-08-19 14:23 ` Tetsuo Handa
2021-08-19 15:10 ` Greg KH
2021-08-16 7:33 ` Christoph Hellwig [this message]
2021-08-16 14:44 ` [PATCH v3] " Tetsuo Handa
[not found] ` <20210817081045.3609-1-hdanton@sina.com>
2021-08-17 10:18 ` Tetsuo Handa
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