From: Greg Kurz Date: Mon, 22 Jan 2018 21:02:05 +0000 (+0100) Subject: 9p/trans_virtio: discard zero-length reply X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=498f0cc811a3fb51e374c8a2d1fe18dd352d1495 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 3.2: adjust context] Signed-off-by: Ben Hutchings --- diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c index 0a05ac1056ef..a10726537d0b 100644 --- a/net/9p/trans_virtio.c +++ b/net/9p/trans_virtio.c @@ -163,7 +163,8 @@ static void req_done(struct virtqueue *vq) P9_DPRINTK(P9_DEBUG_TRANS, ": lookup tag %d\n", rc->tag); req = p9_tag_lookup(chan->client, rc->tag); req->status = REQ_STATUS_RCVD; - p9_client_cb(chan->client, req); + if (len) + p9_client_cb(chan->client, req); } }