Patchwork [3.5.y.z,extended,stable] Patch "virtio: console: return -ENODEV on all read operations after" has been added to staging queue

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Submitter Luis Henriques
Date Aug. 9, 2013, 11:22 a.m.
Message ID <>
Download mbox | patch
Permalink /patch/266008/
State New
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Luis Henriques - Aug. 9, 2013, 11:22 a.m.
This is a note to let you know that I have just added a patch titled

    virtio: console: return -ENODEV on all read operations after

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see



From ba3a8fa7420628aface2a0f04826f5d4d37f73e1 Mon Sep 17 00:00:00 2001
From: Amit Shah <>
Date: Mon, 29 Jul 2013 14:23:21 +0930
Subject: [PATCH] virtio: console: return -ENODEV on all read operations after

commit 96f97a83910cdb9d89d127c5ee523f8fc040a804 upstream.

If a port gets unplugged while a user is blocked on read(), -ENODEV is
returned.  However, subsequent read()s returned 0, indicating there's no
host-side connection (but not indicating the device went away).

This also happened when a port was unplugged and the user didn't have
any blocking operation pending.  If the user didn't monitor the SIGIO
signal, they won't have a chance to find out if the port went away.

Fix by returning -ENODEV on all read()s after the port gets unplugged.
write() already behaves this way.

Signed-off-by: Amit Shah <>
Signed-off-by: Rusty Russell <>
Signed-off-by: Luis Henriques <>
 drivers/char/virtio_console.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)



diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 3bd6d4c..50f0838 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -636,6 +636,10 @@  static ssize_t port_fops_read(struct file *filp, char __user *ubuf,

 	port = filp->private_data;

+	/* Port is hot-unplugged. */
+	if (!port->guest_connected)
+		return -ENODEV;
 	if (!port_has_data(port)) {
 		 * If nothing's connected on the host just return 0 in
@@ -652,7 +656,7 @@  static ssize_t port_fops_read(struct file *filp, char __user *ubuf,
 		if (ret < 0)
 			return ret;
-	/* Port got hot-unplugged. */
+	/* Port got hot-unplugged while we were waiting above. */
 	if (!port->guest_connected)
 		return -ENODEV;