@@ -755,6 +755,10 @@ 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
@@ -771,7 +775,7 @@ 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;
/*
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 unplug to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue This patch is scheduled to be released in version 3.8.13.7. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.8.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From b8cde3b033d277b3f38a65cf15c85822576fc32b Mon Sep 17 00:00:00 2001 From: Amit Shah <amit.shah@redhat.com> Date: Mon, 29 Jul 2013 14:23:21 +0930 Subject: virtio: console: return -ENODEV on all read operations after unplug 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@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/char/virtio_console.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) -- 1.8.1.2