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authorAlan Cox <alan@redhat.com>2009-01-02 13:47:06 +0000
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-02 10:19:40 -0800
commiteff6937a46e096eb35c16a391617b7a5e098a30c (patch)
treebc3d6be6f85a61d27af3f86eb0e8b65b9f83f059
parent39aced68d664291db3324d0fcf0985ab5626aac2 (diff)
tty: USB tty devices can block in tcdrain when unplugged
The underlying problem is that the device methods don't all correctly handle disconnected status and some keep reporting bytes pending which causes tcdrain to stall. When the cable is unplugged they are definitely gone, and as this is true for all USB cables we can fix it in the core usb serial code. Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--drivers/usb/serial/usb-serial.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index aafa684a900..8d518909647 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -339,6 +339,10 @@ static int serial_chars_in_buffer(struct tty_struct *tty)
dbg("%s = port %d", __func__, port->number);
WARN_ON(!port->port.count);
+ /* if the device was unplugged then any remaining characters
+ fell out of the connector ;) */
+ if (port->serial->disconnected)
+ return 0;
/* pass on to the driver specific version of this function */
return port->serial->type->chars_in_buffer(tty);
}