[PATCH 3.16 222/410] 9p/trans_virtio: discard zero-length reply
From: Ben Hutchings
Date: Thu Jun 07 2018 - 10:32:53 EST
3.16.57-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Greg Kurz <groug@xxxxxxxx>
commit 26d99834f89e76514076d9cd06f61e56e6a509b8 upstream.
When a 9p request is successfully flushed, the server is expected to just
mark it as used without sending a 9p reply (ie, without writing data into
the buffer). In this case, virtqueue_get_buf() will return len == 0 and
we must not report a REQ_STATUS_RCVD status to the client, otherwise the
client will erroneously assume the request has not been flushed.
Signed-off-by: Greg Kurz <groug@xxxxxxxx>
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
net/9p/trans_virtio.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/net/9p/trans_virtio.c
+++ b/net/9p/trans_virtio.c
@@ -164,7 +164,8 @@ static void req_done(struct virtqueue *v
p9_debug(P9_DEBUG_TRANS, ": rc %p\n", rc);
p9_debug(P9_DEBUG_TRANS, ": lookup tag %d\n", rc->tag);
req = p9_tag_lookup(chan->client, rc->tag);
- p9_client_cb(chan->client, req, REQ_STATUS_RCVD);
+ if (len)
+ p9_client_cb(chan->client, req, REQ_STATUS_RCVD);
}
}