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| author | Amit Shah <amit.shah@redhat.com> | 2013-07-29 14:23:21 +0930 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-08-14 22:57:07 -0700 |
| commit | a57425e942b49e729a62ccb4d420ae7c83762fe2 (patch) | |
| tree | a4c729b3cf4256b1ebc9c5b8c4d9020a270310b4 | |
| parent | 183c6a6b4ec8efa1a862b07eb4523d8781ae3e44 (diff) | |
| download | lwn-a57425e942b49e729a62ccb4d420ae7c83762fe2.tar.gz lwn-a57425e942b49e729a62ccb4d420ae7c83762fe2.zip | |
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/char/virtio_console.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index 62361ebd9c11..0cd2d50f9a56 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -633,6 +633,10 @@ 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 @@ -649,7 +653,7 @@ 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; /* |