USB: Add URB_FREE_BUFFER flag and the logic behind it (8b3b01c8) · Commits · 戴 / test

USB: Add URB_FREE_BUFFER flag for freeing the transfer buffer In some cases it is not needed that the driver keeps track of the transfer buffer of an URB. It can be simply freed along with the URB itself when the reference count goes down to zero. The new flag URB_FREE_BUFFER enables this behavior. Signed-off-by:

Marcel Holtmann <marcel@holtmann.org> Signed-off-by:

Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/core/urb.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -13,6 +13,9 @@ static void urb_destroy(struct kref *kref)
		{
		struct urb *urb = to_urb(kref);

		if (urb->transfer_flags & URB_FREE_BUFFER)
		kfree(urb->transfer_buffer);

		kfree(urb);
		}

include/linux/usb.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -994,6 +994,7 @@ extern int usb_disabled(void);
		#define URB_ZERO_PACKET 0x0040 /* Finish bulk OUT with short packet */
		#define URB_NO_INTERRUPT 0x0080 /* HINT: no non-error interrupt
		* needed */
		#define URB_FREE_BUFFER 0x0100 /* Free transfer buffer with the URB */

		struct usb_iso_packet_descriptor {
		unsigned int offset;

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