From 9a5861a3d59c64438fe06a66fd6718836bd69703 Mon Sep 17 00:00:00 2001 From: Greg Kurz Date: Mon, 22 Jan 2018 22:02:05 +0100 Subject: [PATCH] 9p/trans_virtio: discard zero-length reply 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 Signed-off-by: Michael S. Tsirkin [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- net/9p/trans_virtio.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c index 2121d9e5f801..bbf55b440da5 100644 --- a/net/9p/trans_virtio.c +++ b/net/9p/trans_virtio.c @@ -164,7 +164,8 @@ static void req_done(struct virtqueue *vq) 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); } }