nbd: clean up return value checking of sock_xmit()

Check if sock_xmit() return 0 is useless because it'll never return
0, comment it and remove such checkings.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Link: https://lore.kernel.org/r/20210916093350.1410403-6-yukuai3@huawei.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 87066ca..1d34560 100644 (file)
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -495,7 +495,8 @@ done:
 }
 
 /*
- *  Send or receive packet.
+ *  Send or receive packet. Return a positive value on success and
+ *  negtive value on failue, and never return 0.
  */
 static int sock_xmit(struct nbd_device *nbd, int index, int send,
                     struct iov_iter *iter, int msg_flags, int *sent)
@@ -621,7 +622,7 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
        result = sock_xmit(nbd, index, 1, &from,
                        (type == NBD_CMD_WRITE) ? MSG_MORE : 0, &sent);
        trace_nbd_header_sent(req, handle);
-       if (result <= 0) {
+       if (result < 0) {
                if (was_interrupted(result)) {
                        /* If we havne't sent anything we can just return BUSY,
                         * however if we have sent something we need to make
@@ -665,7 +666,7 @@ send_pages:
                                skip = 0;
                        }
                        result = sock_xmit(nbd, index, 1, &from, flags, &sent);
-                       if (result <= 0) {
+                       if (result < 0) {
                                if (was_interrupted(result)) {
                                        /* We've already sent the header, we
                                         * have no choice but to set pending and
@@ -717,7 +718,7 @@ static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index)
        reply.magic = 0;
        iov_iter_kvec(&to, READ, &iov, 1, sizeof(reply));
        result = sock_xmit(nbd, index, 0, &to, MSG_WAITALL, NULL);
-       if (result <= 0) {
+       if (result < 0) {
                if (!nbd_disconnected(config))
                        dev_err(disk_to_dev(nbd->disk),
                                "Receive control failed (result %d)\n", result);
@@ -788,7 +789,7 @@ static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index)
                rq_for_each_segment(bvec, req, iter) {
                        iov_iter_bvec(&to, READ, &bvec, 1, bvec.bv_len);
                        result = sock_xmit(nbd, index, 0, &to, MSG_WAITALL, NULL);
-                       if (result <= 0) {
+                       if (result < 0) {
                                dev_err(disk_to_dev(nbd->disk), "Receive data failed (result %d)\n",
                                        result);
                                /*
@@ -1234,7 +1235,7 @@ static void send_disconnects(struct nbd_device *nbd)
                iov_iter_kvec(&from, WRITE, &iov, 1, sizeof(request));
                mutex_lock(&nsock->tx_lock);
                ret = sock_xmit(nbd, i, 1, &from, 0, NULL);
-               if (ret <= 0)
+               if (ret < 0)
                        dev_err(disk_to_dev(nbd->disk),
                                "Send disconnect failed %d\n", ret);
                mutex_unlock(&nsock->tx_lock);