[PATCH] USB: URB_ASYNC_UNLINK flag removed from the kernel

29 July 2005, Cambridge, MA:

This afternoon Alan Stern submitted a patch to remove the URB_ASYNC_UNLINK
flag from the Linux kernel.  Mr. Stern explained, "This flag is a relic
from an earlier, less-well-designed system.  For over a year it hasn't
been used for anything other than printing warning messages."

An anonymous spokesman for the Linux kernel development community
commented, "This is exactly the sort of thing we see happening all the
time.  As the kernel evolves, support for old techniques and old code can
be jettisoned and replaced by newer, better approaches.  Proprietary
operating systems do not have the freedom or flexibility to change so
quickly."

Mr. Stern, a staff member at Harvard University's Rowland Institute who
works on Linux only as a hobby, noted that the patch (labelled as548) did
not update two files, keyspan.c and option.c, in the USB drivers' "serial"
subdirectory.  "Those files need more extensive changes," he remarked.
"They examine the status field of several URBs at times when they're not
supposed to.  That will need to be fixed before the URB_ASYNC_UNLINK flag
is removed."

Greg Kroah-Hartman, the kernel maintainer responsible for overseeing all
of Linux's USB drivers, did not respond to our inquiries or return our
calls.  His only comment was "Applied, thanks."

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

3 files changed, 3 insertions, 6 deletions

diff --git a/drivers/usb/misc/auerswald.c b/drivers/usb/misc/auerswald.c
index 6f7994f5a714..ae4681f9f0ea 100644
--- a/drivers/usb/misc/auerswald.c
+++ b/drivers/usb/misc/auerswald.c
@@ -426,7 +426,7 @@ static int auerchain_submit_urb (pauerchain_t acp, struct urb * urb)
 
 /* cancel an urb which is submitted to the chain
    the result is 0 if the urb is cancelled, or -EINPROGRESS if
-   URB_ASYNC_UNLINK is set and the function is successfully started.
+   the function is successfully started.
 */
 static int auerchain_unlink_urb (pauerchain_t acp, struct urb * urb)
 {
@@ -515,7 +515,6 @@ static void auerchain_unlink_all (pauerchain_t acp)
         acep = acp->active;
         if (acep) {
                 urbp = acep->urbp;
-                urbp->transfer_flags &= ~URB_ASYNC_UNLINK;
                 dbg ("unlink active urb");
                 usb_kill_urb (urbp);
         }
diff --git a/drivers/usb/misc/sisusbvga/sisusb.c b/drivers/usb/misc/sisusbvga/sisusb.c
index 2fd12264fd53..d63ce6c030f3 100644
--- a/drivers/usb/misc/sisusbvga/sisusb.c
+++ b/drivers/usb/misc/sisusbvga/sisusb.c
@@ -229,7 +229,7 @@ sisusb_bulkout_msg(struct sisusb_usb_data *sisusb, int index, unsigned int pipe,
 	usb_fill_bulk_urb(urb, sisusb->sisusb_dev, pipe, data, len,
 		sisusb_bulk_completeout, &sisusb->urbout_context[index]);
 
-	urb->transfer_flags |= (tflags | URB_ASYNC_UNLINK);
+	urb->transfer_flags |= tflags;
 	urb->actual_length = 0;
 
 	if ((urb->transfer_dma = transfer_dma))
@@ -295,7 +295,7 @@ sisusb_bulkin_msg(struct sisusb_usb_data *sisusb, unsigned int pipe, void *data,
 	usb_fill_bulk_urb(urb, sisusb->sisusb_dev, pipe, data, len,
 			sisusb_bulk_completein, sisusb);
 
-	urb->transfer_flags |= (tflags | URB_ASYNC_UNLINK);
+	urb->transfer_flags |= tflags;
 	urb->actual_length = 0;
 
 	if ((urb->transfer_dma = transfer_dma))
diff --git a/drivers/usb/misc/usbtest.c b/drivers/usb/misc/usbtest.c
index fd7fb98e4b20..54799eb0bc60 100644
--- a/drivers/usb/misc/usbtest.c
+++ b/drivers/usb/misc/usbtest.c
@@ -986,7 +986,6 @@ test_ctrl_queue (struct usbtest_dev *dev, struct usbtest_param *param)
 
 		u->context = &context;
 		u->complete = ctrl_complete;
-		u->transfer_flags |= URB_ASYNC_UNLINK;
 	}
 
 	/* queue the urbs */
@@ -1052,7 +1051,6 @@ static int unlink1 (struct usbtest_dev *dev, int pipe, int size, int async)
 	urb = simple_alloc_urb (testdev_to_usbdev (dev), pipe, size);
 	if (!urb)
 		return -ENOMEM;
-	urb->transfer_flags |= URB_ASYNC_UNLINK;
 	urb->context = &completion;
 	urb->complete = unlink1_callback;