| From | Luis Henriques <> | Subject | [PATCH 56/75] virtio: console: return -ENODEV on all read operations after unplug | Date | Wed, 14 Aug 2013 11:36:45 +0100 |
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3.5.7.19 -stable review patch. If anyone has any objections, please let me know.
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From: Amit Shah <amit.shah@redhat.com>
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: Luis Henriques <luis.henriques@canonical.com> --- 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; /* -- 1.8.3.2
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