* [PATCH AUTOSEL 5.3 85/89] nbd: fix possible sysfs duplicate warning
[not found] <20191018220324.8165-1-sashal@kernel.org>
@ 2019-10-18 22:03 ` Sasha Levin
0 siblings, 0 replies; only message in thread
From: Sasha Levin @ 2019-10-18 22:03 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Xiubo Li, Mike Christie, Josef Bacik, Jens Axboe, Sasha Levin,
linux-block, nbd
From: Xiubo Li <xiubli@redhat.com>
[ Upstream commit 862488105b84ca744b3d8ff131e0fcfe10644be1 ]
1. nbd_put takes the mutex and drops nbd->ref to 0. It then does
idr_remove and drops the mutex.
2. nbd_genl_connect takes the mutex. idr_find/idr_for_each fails
to find an existing device, so it does nbd_dev_add.
3. just before the nbd_put could call nbd_dev_remove or not finished
totally, but if nbd_dev_add try to add_disk, we can hit:
debugfs: Directory 'nbd1' with parent 'block' already present!
This patch will make sure all the disk add/remove stuff are done
by holding the nbd_index_mutex lock.
Reported-by: Mike Christie <mchristi@redhat.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/block/nbd.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 0b727f7432f9e..bd164192045b0 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -230,8 +230,8 @@ static void nbd_put(struct nbd_device *nbd)
if (refcount_dec_and_mutex_lock(&nbd->refs,
&nbd_index_mutex)) {
idr_remove(&nbd_index_idr, nbd->index);
- mutex_unlock(&nbd_index_mutex);
nbd_dev_remove(nbd);
+ mutex_unlock(&nbd_index_mutex);
}
}
--
2.20.1
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