SUNRPC: ensure correct error is reported by xs_tcp_setup_socket()

NeilBrown · trondmypd · commit 6ea44adce915 · 2017-05-31T12:26:44.000-04:00
If you attempt a TCP mount from an host that is unreachable in a way that triggers an immediate error from kernel_connect(), that error does not propagate up, instead EAGAIN is reported. This results in call_connect_status receiving the wrong error. A case that it easy to demonstrate is to attempt to mount from an address that results in ENETUNREACH, but first deleting any default route. Without this patch, the mount.nfs process is persistently runnable and is hard to kill. With this patch it exits as it should. The problem is caused by the fact that xs_tcp_force_close() eventually calls xprt_wake_pending_tasks(xprt, -EAGAIN); which causes an error return of -EAGAIN. so when xs_tcp_setup_sock() calls xprt_wake_pending_tasks(xprt, status); the status is ignored. Fixes: 4efdd92 ("SUNRPC: Remove TCP client connection reset hack") Signed-off-by: NeilBrown <neilb@suse.com> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
@@ -2432,7 +2432,12 @@ static void xs_tcp_setup_socket(struct work_struct *work)
 	case -ENETUNREACH:
 	case -EADDRINUSE:
 	case -ENOBUFS:
-		/* retry with existing socket, after a delay */
+		/*
+		 * xs_tcp_force_close() wakes tasks with -EIO.
+		 * We need to wake them first to ensure the
+		 * correct error code.
+		 */
+		xprt_wake_pending_tasks(xprt, status);
 		xs_tcp_force_close(xprt);
 		goto out;
 	}
