[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>

1 files changed, 10 insertions, 4 deletions

diff --git a/drivers/usb/serial/ipw.c b/drivers/usb/serial/ipw.c
index 11105d74f461..85e242459c27 100644
--- a/drivers/usb/serial/ipw.c
+++ b/drivers/usb/serial/ipw.c
@@ -399,16 +399,21 @@ static int ipw_write(struct usb_serial_port *port, const unsigned char *buf, int
                 dbg("%s - write request of 0 bytes", __FUNCTION__);
                 return 0;
         }
-        
-        /* Racy and broken, FIXME properly! */
-        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;
+        }
+        port->write_urb_busy = 1;
+        spin_unlock(&port->lock);
 
         count = min(count, port->bulk_out_size);
         memcpy(port->bulk_out_buffer, buf, count);
 
         dbg("%s count now:%d", __FUNCTION__, count);
-        
+
         usb_fill_bulk_urb(port->write_urb, dev,
                           usb_sndbulkpipe(dev, port->bulk_out_endpointAddress),
                           port->write_urb->transfer_buffer,
@@ -418,6 +423,7 @@ static int ipw_write(struct usb_serial_port *port, const unsigned char *buf, int
 
         ret = usb_submit_urb(port->write_urb, GFP_ATOMIC);
         if (ret != 0) {
+                port->write_urb_busy = 0;
                 dbg("%s - usb_submit_urb(write bulk) failed with error = %d", __FUNCTION__, ret);
                 return ret;
         }