[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, 16 insertions, 8 deletions

diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c
index 99214aa3cd19..ddde5fb13f6b 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -174,10 +174,14 @@ int usb_serial_generic_write(struct usb_serial_port *port, const unsigned char *
 
         /* 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 @@ int usb_serial_generic_write(struct usb_serial_port *port, const unsigned char *
                                      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 usb_serial_generic_write_room (struct usb_serial_port *port)
         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 @@ int usb_serial_generic_chars_in_buffer (struct usb_serial_port *port)
         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 @@ void usb_serial_generic_write_bulk_callback (struct urb *urb, struct pt_regs *re
 
         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;