When try to get the lock failed, before return, execute the nbd_config_put() to decrease the nbd->config_refs. If the nbd->config_refs is added but not decreased. Then will not execute nbd_clear_sock() in nbd_config_put(). bd->task_setup will not be cleared away. Finally, print"Device being setup by another task" in nbd_add_sock() and nbd device can not be reused. Fixes: 8f3ea35929a0 ("nbd: handle unexpected replies better") Signed-off-by: Sun Ke <sunke32@xxxxxxxxxx> --- drivers/block/nbd.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index e21d2de..a69a90a 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -357,8 +357,10 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req, } config = nbd->config; - if (!mutex_trylock(&cmd->lock)) + if (!mutex_trylock(&cmd->lock)) { + nbd_config_put(nbd); return BLK_EH_RESET_TIMER; + } if (config->num_connections > 1) { dev_err_ratelimited(nbd_to_dev(nbd), -- 2.7.4