linux-kernel - [PATCH 3.16 227/366] virtio_console: reset on out of memory

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Message-ID: <lsq.1539530741.822996228@decadent.org.uk>
Date:   Sun, 14 Oct 2018 16:25:41 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Michael S. Tsirkin" <mst@...hat.com>
Subject: [PATCH 3.16 227/366] virtio_console: reset on out of memory

3.16.60-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: "Michael S. Tsirkin" <mst@...hat.com>

commit 5c60300d68da32ca77f7f978039dc72bfc78b06b upstream.

When out of memory and we can't add ctrl vq buffers,
probe fails. Unfortunately the error handling is
out of spec: it calls del_vqs without bothering
to reset the device first.

To fix, call the full cleanup function in this case.

Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/char/virtio_console.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -2073,6 +2073,7 @@ static int virtcons_probe(struct virtio_

 	spin_lock_init(&portdev->ports_lock);
 	INIT_LIST_HEAD(&portdev->ports);
+	INIT_LIST_HEAD(&portdev->list);

 	INIT_WORK(&portdev->config_work, &config_work_handler);
 	INIT_WORK(&portdev->control_work, &control_work_handler);
@@ -2088,8 +2089,15 @@ static int virtcons_probe(struct virtio_
 		if (!nr_added_bufs) {
 			dev_err(&vdev->dev,
 				"Error allocating buffers for control queue\n");
-			err = -ENOMEM;
-			goto free_vqs;
+			/*
+			 * The host might want to notify mgmt sw about device
+			 * add failure.
+			 */
+			__send_control_msg(portdev, VIRTIO_CONSOLE_BAD_ID,
+					   VIRTIO_CONSOLE_DEVICE_READY, 0);
+			/* Device was functional: we need full cleanup. */
+			virtcons_remove(vdev);
+			return -ENOMEM;
 		}
 	} else {
 		/*
@@ -2120,11 +2128,6 @@ static int virtcons_probe(struct virtio_

 	return 0;

-free_vqs:
-	/* The host might want to notify mgmt sw about device add failure */
-	__send_control_msg(portdev, VIRTIO_CONSOLE_BAD_ID,
-			   VIRTIO_CONSOLE_DEVICE_READY, 0);
-	remove_vqs(portdev);
 free_chrdev:
 	unregister_chrdev(portdev->chr_major, "virtio-portsdev");
 free: