3.8.13.7 -stable review patch. If anyone has any objections, please let me
know.
------------------
From: Amit Shah <amit.s...@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.s...@redhat.com>
Signed-off-by: Rusty Russell <ru...@rustcorp.com.au>
Signed-off-by: Kamal Mostafa <ka...@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 62834bc..12829ae 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -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;
/*
--
1.8.1.2
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