net/9p: Switch to wait_event_killable()

Because userspace gets Very Unhappy when calls like stat() and execve()
return -EINTR on 9p filesystem mounts. For instance, when bash is
looking in PATH for things to execute and some SIGCHLD interrupts
stat(), bash can throw a spurious 'command not found' since it doesn't
retry the stat().

In practice, hitting the problem is rare and needs a really
slow/bogged down 9p server.

Cc: stable@vger.kernel.org
Signed-off-by: Tuomas Tynkkynen <tuomas@tuxera.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

net/9p/client.c

@@ -773,8 +773,7 @@ p9_client_rpc(struct p9_client *c, int8_t type, const char *fmt, ...)
 	}
 again:
 	/* Wait for the response */
-	err = wait_event_interruptible(*req->wq,
-				       req->status >= REQ_STATUS_RCVD);
+	err = wait_event_killable(*req->wq, req->status >= REQ_STATUS_RCVD);
 
 	/*
 	 * Make sure our req is coherent with regard to updates in other

net/9p/trans_virtio.c

@@ -286,8 +286,8 @@ p9_virtio_request(struct p9_client *client, struct p9_req_t *req)
 		if (err == -ENOSPC) {
 			chan->ring_bufs_avail = 0;
 			spin_unlock_irqrestore(&chan->lock, flags);
-			err = wait_event_interruptible(*chan->vc_wq,
-							chan->ring_bufs_avail);
+			err = wait_event_killable(*chan->vc_wq,
+						  chan->ring_bufs_avail);
 			if (err  == -ERESTARTSYS)
 				return err;
 
@@ -327,7 +327,7 @@ static int p9_get_mapped_pages(struct virtio_chan *chan,
 		 * Other zc request to finish here
 		 */
 		if (atomic_read(&vp_pinned) >= chan->p9_max_pages) {
-			err = wait_event_interruptible(vp_wq,
+			err = wait_event_killable(vp_wq,
 			      (atomic_read(&vp_pinned) < chan->p9_max_pages));
 			if (err == -ERESTARTSYS)
 				return err;
@@ -471,8 +471,8 @@ p9_virtio_zc_request(struct p9_client *client, struct p9_req_t *req,
 		if (err == -ENOSPC) {
 			chan->ring_bufs_avail = 0;
 			spin_unlock_irqrestore(&chan->lock, flags);
-			err = wait_event_interruptible(*chan->vc_wq,
-						       chan->ring_bufs_avail);
+			err = wait_event_killable(*chan->vc_wq,
+						  chan->ring_bufs_avail);
 			if (err  == -ERESTARTSYS)
 				goto err_out;
 
@@ -489,8 +489,7 @@ p9_virtio_zc_request(struct p9_client *client, struct p9_req_t *req,
 	virtqueue_kick(chan->vq);
 	spin_unlock_irqrestore(&chan->lock, flags);
 	p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n");
-	err = wait_event_interruptible(*req->wq,
-				       req->status >= REQ_STATUS_RCVD);
+	err = wait_event_killable(*req->wq, req->status >= REQ_STATUS_RCVD);
 	/*
 	 * Non kernel buffers are pinned, unpin them
 	 */

net/9p/trans_xen.c

@@ -156,8 +156,8 @@ static int p9_xen_request(struct p9_client *client, struct p9_req_t *p9_req)
 	ring = &priv->rings[num];
 
 again:
-	while (wait_event_interruptible(ring->wq,
-					p9_xen_write_todo(ring, size)) != 0)
+	while (wait_event_killable(ring->wq,
+				   p9_xen_write_todo(ring, size)) != 0)
 		;
 
 	spin_lock_irqsave(&ring->lock, flags);