This is a note to let you know that I've just added the patch titled
virtio: console: return -ENODEV on all read operations after unplug
to the 3.4-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:
virtio-console-return-enodev-on-all-read-operations-after-unplug.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 96f97a83910cdb9d89d127c5ee523f8fc040a804 Mon Sep 17 00:00:00 2001
From: Amit Shah <amit.shah@xxxxxxxxxx>
Date: Mon, 29 Jul 2013 14:23:21 +0930
Subject: virtio: console: return -ENODEV on all read operations after unplug
From: Amit Shah <amit.shah@xxxxxxxxxx>
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 <amit.shah@xxxxxxxxxx>
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/char/virtio_console.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -633,6 +633,10 @@ static ssize_t port_fops_read(struct fil
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
@@ -649,7 +653,7 @@ static ssize_t port_fops_read(struct fil
if (ret < 0)
return ret;
}
- /* Port got hot-unplugged. */
+ /* Port got hot-unplugged while we were waiting above. */
if (!port->guest_connected)
return -ENODEV;
/*
Patches currently in stable-queue which might be from amit.shah@xxxxxxxxxx are
queue-3.4/virtio-console-fix-raising-sigio-after-port-unplug.patch
queue-3.4/virtio-console-clean-up-port-data-immediately-at-time-of-unplug.patch
queue-3.4/virtio-console-fix-race-in-port_fops_open-and-port-unplug.patch
queue-3.4/virtio-console-return-enodev-on-all-read-operations-after-unplug.patch
queue-3.4/virtio-console-fix-race-with-port-unplug-and-open-close.patch
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