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| author | Mike Christie <mchristi@redhat.com> | 2019-12-08 16:51:50 -0600 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-12-31 12:38:07 +0100 |
| commit | d1db913b044f0a0693d8ee283d26b81d536efcd5 (patch) | |
| tree | 215fe7ac2e32466ca911b643db106fd1485d9bb0 | |
| parent | 5a07ace7375231e6eb79667a2784c0bf023f87da (diff) | |
| download | linux-stable-d1db913b044f0a0693d8ee283d26b81d536efcd5.tar.gz linux-stable-d1db913b044f0a0693d8ee283d26b81d536efcd5.tar.bz2 linux-stable-d1db913b044f0a0693d8ee283d26b81d536efcd5.zip | |
nbd: fix shutdown and recv work deadlock v2
commit 1c05839aa973cfae8c3db964a21f9c0eef8fcc21 upstream.
This fixes a regression added with:
commit e9e006f5fcf2bab59149cb38a48a4817c1b538b4
Author: Mike Christie <mchristi@redhat.com>
Date: Sun Aug 4 14:10:06 2019 -0500
nbd: fix max number of supported devs
where we can deadlock during device shutdown. The problem occurs if
the recv_work's nbd_config_put occurs after nbd_start_device_ioctl has
returned and the userspace app has droppped its reference via closing
the device and running nbd_release. The recv_work nbd_config_put call
would then drop the refcount to zero and try to destroy the config which
would try to do destroy_workqueue from the recv work.
This patch just has nbd_start_device_ioctl do a flush_workqueue when it
wakes so we know after the ioctl returns running works have exited. This
also fixes a possible race where we could try to reuse the device while
old recv_works are still running.
Cc: stable@vger.kernel.org
Fixes: e9e006f5fcf2 ("nbd: fix max number of supported devs")
Signed-off-by: Mike Christie <mchristi@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/block/nbd.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 929bd255a290..4c661ad91e7d 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -1234,10 +1234,10 @@ static int nbd_start_device_ioctl(struct nbd_device *nbd, struct block_device *b mutex_unlock(&nbd->config_lock); ret = wait_event_interruptible(config->recv_wq, atomic_read(&config->recv_threads) == 0); - if (ret) { + if (ret) sock_shutdown(nbd); - flush_workqueue(nbd->recv_workq); - } + flush_workqueue(nbd->recv_workq); + mutex_lock(&nbd->config_lock); bd_set_size(bdev, 0); /* user requested, ignore socket errors */ |