[PATCH] USB: Converting cdc acm to a ring queue

this patch by David converts the sending queue of the CDC ACM driver
to a queue of URBs. This is needed for quicker devices. Please apply.
Signed-Off-By: Oliver Neukum <oliver@neukum.name>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

 drivers/usb/class/cdc-acm.c |  229 ++++++++++++++++++++++++++++++--------------
 drivers/usb/class/cdc-acm.h |   33 +++++-
 2 files changed, 185 insertions(+), 77 deletions(-)

drivers/usb/class/cdc-acm.h

@@ -59,6 +59,9 @@
  * when processing onlcr, so we only need 2 buffers.
  */
 #define ACM_NWB  2
+#define ACM_NRU  16
+#define ACM_NRB  16
+
 struct acm_wb {
 	unsigned char *buf;
 	dma_addr_t dmah;
@@ -66,22 +69,43 @@ struct acm_wb {
 	int use;
 };
 
+struct acm_rb {
+	struct list_head	list;
+	int			size;
+	unsigned char		*base;
+	dma_addr_t		dma;
+};
+
+struct acm_ru {
+	struct list_head	list;
+	struct acm_rb		*buffer;
+	struct urb		*urb;
+	struct acm		*instance;
+};
+
 struct acm {
 	struct usb_device *dev;				/* the corresponding usb device */
 	struct usb_interface *control;			/* control interface */
 	struct usb_interface *data;			/* data interface */
 	struct tty_struct *tty;				/* the corresponding tty */
-	struct urb *ctrlurb, *readurb, *writeurb;	/* urbs */
-	u8 *ctrl_buffer, *read_buffer;			/* buffers of urbs */
-	dma_addr_t ctrl_dma, read_dma;			/* dma handles of buffers */
+	struct urb *ctrlurb, *writeurb;			/* urbs */
+	u8 *ctrl_buffer;				/* buffers of urbs */
+	dma_addr_t ctrl_dma;				/* dma handles of buffers */
 	struct acm_wb wb[ACM_NWB];
+	struct acm_ru ru[ACM_NRU];
+	struct acm_rb rb[ACM_NRB];
+	int rx_endpoint;
+	spinlock_t read_lock;
+	struct list_head spare_read_urbs;
+	struct list_head spare_read_bufs;
+	struct list_head filled_read_bufs;
 	int write_current;				/* current write buffer */
 	int write_used;					/* number of non-empty write buffers */
 	int write_ready;				/* write urb is not running */
 	spinlock_t write_lock;
 	struct usb_cdc_line_coding line;		/* bits, stop, parity */
 	struct work_struct work;			/* work queue entry for line discipline waking up */
-	struct tasklet_struct bh;			/* rx processing */
+	struct tasklet_struct urb_task;                 /* rx processing */
 	spinlock_t throttle_lock;			/* synchronize throtteling and read callback */
 	unsigned int ctrlin;				/* input control lines (DCD, DSR, RI, break, overruns) */
 	unsigned int ctrlout;				/* output control lines (DTR, RTS) */
@@ -91,7 +115,6 @@ struct acm {
 	unsigned int minor;				/* acm minor number */
 	unsigned char throttle;				/* throttled by tty layer */
 	unsigned char clocal;				/* termios CLOCAL */
-	unsigned char resubmit_to_unthrottle;		/* throtteling has disabled the read urb */
 	unsigned int ctrl_caps;				/* control capabilities from the class specific header */
 };