On 2021/09/22 17:22, Ming Lei wrote:

On Sun, Sep 19, 2021 at 06:34:28PM +0800, yukuai (C) wrote:

quoted

On 2021/09/16 17:33, Yu Kuai wrote:

quoted

The sock that clent send request in nbd_send_cmd() and receive reply
in nbd_read_stat() should be the same.

Signed-off-by: Yu Kuai <redacted>
---
   drivers/block/nbd.c | 4 ++++
   1 file changed, 4 insertions(+)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 614c6ab2b8fe..c724a5bd7fa4 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c

@@ -746,6 +746,10 @@ static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index)
   		ret = -ENOENT;
   		goto out;
   	}
+	if (cmd->index != index) {
+		dev_err(disk_to_dev(nbd->disk), "Unexpected reply %d from different sock %d (expected %d)",
+			tag, index, cmd->index);
+	}
   	if (cmd->cmd_cookie != nbd_handle_to_cookie(handle)) {
   		dev_err(disk_to_dev(nbd->disk), "Double reply on req %p, cmd_cookie %u, handle cookie %u\n",
   			req, cmd->cmd_cookie, nbd_handle_to_cookie(handle));

Hi, Ming

Any suggestions about this patch?

I think this one relies on nbd protocol between server and client, and
does the protocol require both request and reply xmitted via same
socket?

I searched nbd-server source code, and found that socket_read() and
send_reply->socket_write() are always come in pares and using the same
socket.

BTW, if server reply a read request from a unexpected sock, then
nbd_read_stat() might stuck in receiving the read data. And for worse,
nbd_read_stat() can mistake the normal reply message for the read data
afterwards and corrupt client.

Thanks,
Kuai