nbd: protect cmd->status with cmd->lock

We already do this for the most part, except in timeout and clear_req.
For the timeout case we take the lock after we grab a ref on the config,
but that isn't really necessary because we're safe to touch the cmd at
this point, so just move the order around.

For the clear_req cause this is initiated by the user, so again is safe.

Reviewed-by: Mike Christie <mchristi@redhat.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 478aa86..f9e1895 100644 (file)
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -385,17 +385,16 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req,
        struct nbd_device *nbd = cmd->nbd;
        struct nbd_config *config;
 
+       if (!mutex_trylock(&cmd->lock))
+               return BLK_EH_RESET_TIMER;
+
        if (!refcount_inc_not_zero(&nbd->config_refs)) {
                cmd->status = BLK_STS_TIMEOUT;
+               mutex_unlock(&cmd->lock);
                goto done;
        }
        config = nbd->config;
 
-       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),
                                    "Connection timed out, retrying (%d/%d alive)\n",
@@ -792,7 +791,10 @@ static bool nbd_clear_req(struct request *req, void *data, bool reserved)
 {
        struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);
 
+       mutex_lock(&cmd->lock);
        cmd->status = BLK_STS_IOERR;
+       mutex_unlock(&cmd->lock);
+
        blk_mq_complete_request(req);
        return true;
 }