Patch "SUNRPC: ensure correct error is reported by xs_tcp_setup_socket()" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

SUNRPC: ensure correct error is reported by xs_tcp_setup_socket()

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
sunrpc-ensure-correct-error-is-reported-by-xs_tcp_setup_socket.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: NeilBrown <[email protected]>
Date: Thu, 25 May 2017 17:00:32 +1000
Subject: SUNRPC: ensure correct error is reported by xs_tcp_setup_socket()

From: NeilBrown <[email protected]>

[ Upstream commit 6ea44adce91526700535b3150f77f8639ae8c82d ]

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.

---
 net/sunrpc/xprtsock.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

@@ -2384,7 +2384,12 @@ static void xs_tcp_setup_socket(struct w
 	case -EHOSTUNREACH:
 	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;
 	}

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/vfs-close-race-between-getcwd-and-d_move.patch queue-4.9/sunrpc-ensure-correct-error-is-reported-by-xs_tcp_setup_socket.patch