9p/rdma: do not disconnect on down_interruptible EAGAIN

BugLink: https://bugs.launchpad.net/bugs/1836668

[ Upstream commit 8b894adb ]

9p/rdma would sometimes drop the connection and display errors in
recv_done when the user does ^C.
The errors were caused by recv buffers that were posted at the time
of disconnect, and we just do not want to disconnect when
down_interruptible is... interrupted.

Link: http://lkml.kernel.org/r/1535625307-18019-1-git-send-email-asmadeus@codewreck.orgSigned-off-by: Dominique Martinet <dominique.martinet@cea.fr>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

net/9p/trans_rdma.c

@@ -476,7 +476,7 @@ static int rdma_request(struct p9_client *client, struct p9_req_t *req)
 
 	err = post_recv(client, rpl_context);
 	if (err) {
-		p9_debug(P9_DEBUG_FCALL, "POST RECV failed\n");
+		p9_debug(P9_DEBUG_ERROR, "POST RECV failed: %d\n", err);
 		goto recv_error;
 	}
 	/* remove posted receive buffer from request structure */
@@ -544,7 +544,7 @@ static int rdma_request(struct p9_client *client, struct p9_req_t *req)
  recv_error:
 	kfree(rpl_context);
 	spin_lock_irqsave(&rdma->req_lock, flags);
-	if (rdma->state < P9_RDMA_CLOSING) {
+	if (err != -EINTR && rdma->state < P9_RDMA_CLOSING) {
 		rdma->state = P9_RDMA_CLOSING;
 		spin_unlock_irqrestore(&rdma->req_lock, flags);
 		rdma_disconnect(rdma->cm_id);