[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, 11 insertions, 5 deletions

diff --git a/drivers/usb/serial/ir-usb.c b/drivers/usb/serial/ir-usb.c
index 59f234df5f89..937b2fdd7171 100644
--- a/drivers/usb/serial/ir-usb.c
+++ b/drivers/usb/serial/ir-usb.c
@@ -341,10 +341,14 @@ static int ir_write (struct usb_serial_port *port, const unsigned char *buf, int
         if (count == 0)
                 return 0;
 
-        if (port->write_urb->status == -EINPROGRESS) {
-                dbg ("%s - already writing", __FUNCTION__);
+        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);
 
         transfer_buffer = port->write_urb->transfer_buffer;
         transfer_size = min(count, port->bulk_out_size - 1);
@@ -374,9 +378,10 @@ static int ir_write (struct usb_serial_port *port, const unsigned char *buf, int
         port->write_urb->transfer_flags = URB_ZERO_PACKET;
 
         result = usb_submit_urb (port->write_urb, GFP_ATOMIC);
-        if (result)
+        if (result) {
+                port->write_urb_busy = 0;
                 dev_err(&port->dev, "%s - failed submitting write urb, error %d\n", __FUNCTION__, result);
-        else
+        } else
                 result = transfer_size;
 
         return result;
@@ -387,7 +392,8 @@ static void ir_write_bulk_callback (struct urb *urb, struct pt_regs *regs)
         struct usb_serial_port *port = (struct usb_serial_port *)urb->context;
 
         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;