3.2.51-rc1 review patch. If anyone has any objections, please let me know.
------------------
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: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
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
@@ -637,6 +637,10 @@ 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
@@ -653,7 +657,7 @@ 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;
/*
--
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