[PATCH] USB: add ability for usb-serial drivers to determine if their write urb is currently being used.
This removes a lot of racy and buggy code by trying to check the status of the urb.
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c
index 99214aa..ddde5fb 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -174,10 +174,14 @@
/* only do something if we have a bulk out endpoint */
if (serial->num_bulk_out) {
- if (port->write_urb->status == -EINPROGRESS) {
+ spin_lock(&port->lock);
+ if (port->write_urb_busy) {
+ spin_unlock(&port->lock);
dbg("%s - already writing", __FUNCTION__);
- return (0);
+ return 0;
}
+ port->write_urb_busy = 1;
+ spin_unlock(&port->lock);
count = (count > port->bulk_out_size) ? port->bulk_out_size : count;
@@ -195,17 +199,20 @@
usb_serial_generic_write_bulk_callback), port);
/* send the data out the bulk port */
+ port->write_urb_busy = 1;
result = usb_submit_urb(port->write_urb, GFP_ATOMIC);
- if (result)
+ if (result) {
dev_err(&port->dev, "%s - failed submitting write urb, error %d\n", __FUNCTION__, result);
- else
+ /* don't have to grab the lock here, as we will retry if != 0 */
+ port->write_urb_busy = 0;
+ } else
result = count;
return result;
}
/* no bulk out, so return 0 bytes written */
- return (0);
+ return 0;
}
int usb_serial_generic_write_room (struct usb_serial_port *port)
@@ -214,9 +221,9 @@
int room = 0;
dbg("%s - port %d", __FUNCTION__, port->number);
-
+
if (serial->num_bulk_out) {
- if (port->write_urb->status != -EINPROGRESS)
+ if (port->write_urb_busy)
room = port->bulk_out_size;
}
@@ -232,7 +239,7 @@
dbg("%s - port %d", __FUNCTION__, port->number);
if (serial->num_bulk_out) {
- if (port->write_urb->status == -EINPROGRESS)
+ if (port->write_urb_busy)
chars = port->write_urb->transfer_buffer_length;
}
@@ -291,6 +298,7 @@
dbg("%s - port %d", __FUNCTION__, port->number);
+ port->write_urb_busy = 0;
if (urb->status) {
dbg("%s - nonzero write bulk status received: %d", __FUNCTION__, urb->status);
return;