[PATCH] usbcore misc cleanup

This has minor usbcore cleanups:

DOC:
    - the changes passing a usb_interface to driver probe() and disconnect()
      weren't reflected in their adjacent docs.  likewise they still said
      it was possible to get a null usb_device_id (no more).

    - the (root) hub API restrictions from rmk's ARM patch weren't
      flagged

    - mention the non-dma-coherent cache issue for usb_buffer_alloc()

    - mention disconnect() cleanup issue with usb_{control,bulk}_msg()
      [ you can't cancel those urbs from disconnect() ]

CODE
    - make driver ioctl() use 'usb_interface' too ... this update
      also resolves an old 'one instance per device' bad assumption

    - module locking on driver->ioctl() was goofy, kept BKL way too
      long and didn't try_inc_mod_count() like the rest of usbcore

    - hcd unlink code treated iso inappropriately like interrupt;
      only interrupt still wants that automagic mode

    - move iso init out of ohci into shared submit_urb logic

    - remove interrupt transfer length restriction; hcds that don't
      handle packetization (just like bulk :) should be updated,
      but device drivers won't care for now.

drivers/usb/core/devio.c

@@ -1067,6 +1067,10 @@ static int proc_ioctl (struct dev_state *ps, void *arg)
        /* disconnect kernel driver from interface, leaving it unbound.  */
        case USBDEVFS_DISCONNECT:
 		/* this function is voodoo. */
+		/* which function ... usb_device_remove()?
+		 * FIXME either the module lock (BKL) should be involved
+		 * here too, or the 'default' case below is broken
+		 */
 		driver = ifp->driver;
 		if (driver) {
 			dbg ("disconnect '%s' from dev %d interface %d",
@@ -1083,24 +1087,26 @@ static int proc_ioctl (struct dev_state *ps, void *arg)
 
 	/* talk directly to the interface's driver */
 	default:
-		lock_kernel(); /* against module unload */
+		/* BKL used here to protect against changing the binding
+		 * of this driver to this device, as well as unloading its
+		 * driver module.
+		 */
+		lock_kernel ();
 		driver = ifp->driver;
 		if (driver == 0 || driver->ioctl == 0) {
 			unlock_kernel();
 			retval = -ENOSYS;
 		} else {
-			if (ifp->driver->owner) {
-				__MOD_INC_USE_COUNT(ifp->driver->owner);
-				unlock_kernel();
-			}
-			/* ifno might usefully be passed ... */
-                       retval = driver->ioctl (ps->dev, ctrl.ioctl_code, buf);
-			/* size = min_t(int, size, retval)? */
-			if (ifp->driver->owner) {
-				__MOD_DEC_USE_COUNT(ifp->driver->owner);
-			} else {
+			if (driver->owner
+					&& !try_inc_mod_count (driver->owner)) {
 				unlock_kernel();
+				retval = -ENOSYS;
+				break;
 			}
+			unlock_kernel ();
+			retval = driver->ioctl (ifp, ctrl.ioctl_code, buf);
+			if (driver->owner)
+				__MOD_DEC_USE_COUNT (driver->owner);
 		}
 		
 		if (retval == -ENOIOCTLCMD)

drivers/usb/core/hcd.c

@@ -1024,6 +1024,11 @@ static int hcd_submit_urb (struct urb *urb, int mem_flags)
 	 */
 	urb = usb_get_urb (urb);
 	if (urb->dev == hcd->self.root_hub) {
+		/* NOTE:  requirement on hub callers (usbfs and the hub
+		 * driver, for now) that URBs' urb->transfer_buffer be
+		 * valid and usb_buffer_{sync,unmap}() not be needed, since
+		 * they could clobber root hub response data.
+		 */
 		urb->transfer_flags |= URB_NO_DMA_MAP;
 		return rh_urb_enqueue (hcd, urb);
 	}
@@ -1132,11 +1137,11 @@ static int hcd_unlink_urb (struct urb *urb)
 		goto done;
 	}
 
-	/* For non-periodic transfers, any status except -EINPROGRESS means
-	 * the HCD has already started to unlink this URB from the hardware.
-	 * In that case, there's no more work to do.
+	/* Except for interrupt transfers, any status except -EINPROGRESS
+	 * means the HCD already started to unlink this URB from the hardware.
+	 * So there's no more work to do.
 	 *
-	 * For periodic transfers, this is the only way to trigger unlinking
+	 * For interrupt transfers, this is the only way to trigger unlinking
 	 * from the hardware.  Since we (currently) overload urb->status to
 	 * tell the driver to unlink, error status might get clobbered ...
 	 * unless that transfer hasn't yet restarted.  One such case is when
@@ -1144,14 +1149,11 @@ static int hcd_unlink_urb (struct urb *urb)
 	 *
 	 * FIXME use an URB_UNLINKED flag to match URB_TIMEOUT_KILLED
 	 */
-	switch (usb_pipetype (urb->pipe)) {
-	case PIPE_CONTROL:
-	case PIPE_BULK:
-		if (urb->status != -EINPROGRESS) {
+	if (urb->status != -EINPROGRESS
+			&& usb_pipetype (urb->pipe) != PIPE_INTERRUPT) {
 		retval = -EINVAL;
 		goto done;
 	}
-	}
 
 	/* maybe set up to block on completion notification */
 	if ((urb->transfer_flags & USB_TIMEOUT_KILLED))

drivers/usb/core/hub.c

@@ -547,8 +547,11 @@ static int hub_probe(struct usb_interface *intf, const struct usb_device_id *id)
 	return -ENODEV;
 }
 
-static int hub_ioctl(struct usb_device *hub, unsigned int code, void *user_data)
+static int
+hub_ioctl(struct usb_interface *intf, unsigned int code, void *user_data)
 {
+	struct usb_device *hub = interface_to_usbdev (intf);
+
 	/* assert ifno == 0 (part of hub spec) */
 	switch (code) {
 	case USBDEVFS_HUB_PORTINFO: {

drivers/usb/core/message.c

@@ -123,6 +123,9 @@ int usb_internal_control_msg(struct usb_device *usb_dev, unsigned int pipe,
  *	Don't use this function from within an interrupt context, like a
  *	bottom half handler.  If you need an asynchronous message, or need to send
  *	a message from within interrupt context, use usb_submit_urb()
+ *      If a thread in your driver uses this call, make sure your disconnect()
+ *      method can wait for it to complete.  Since you don't have a handle on
+ *      the URB used, you can't cancel the request.
  */
 int usb_control_msg(struct usb_device *dev, unsigned int pipe, __u8 request, __u8 requesttype,
 			 __u16 value, __u16 index, void *data, __u16 size, int timeout)
@@ -170,6 +173,9 @@ int usb_control_msg(struct usb_device *dev, unsigned int pipe, __u8 request, __u
  *	Don't use this function from within an interrupt context, like a
  *	bottom half handler.  If you need an asynchronous message, or need to
  *	send a message from within interrupt context, use usb_submit_urb()
+ *      If a thread in your driver uses this call, make sure your disconnect()
+ *      method can wait for it to complete.  Since you don't have a handle on
+ *      the URB used, you can't cancel the request.
  */
 int usb_bulk_msg(struct usb_device *usb_dev, unsigned int pipe, 
 			void *data, int len, int *actual_length, int timeout)

drivers/usb/core/urb.c

@@ -232,22 +232,19 @@ int usb_submit_urb(struct urb *urb, int mem_flags)
 		return -EMSGSIZE;
 	}
 
+	/* periodic transfers limit size per frame/uframe,
+	 * but drivers only control those sizes for ISO.
+	 * while we're checking, initialize return status.
+	 */
+	if (temp == PIPE_ISOCHRONOUS) {
+		int	n, len;
+
 		/* "high bandwidth" mode, 1-3 packets/uframe? */
 		if (dev->speed == USB_SPEED_HIGH) {
-		int	mult;
-		switch (temp) {
-		case PIPE_ISOCHRONOUS:
-		case PIPE_INTERRUPT:
-			mult = 1 + ((max >> 11) & 0x03);
+			int	mult = 1 + ((max >> 11) & 0x03);
 			max &= 0x03ff;
 			max *= mult;
 		}
-	}
-
-	/* periodic transfers limit size per frame/uframe */
-	switch (temp) {
-	case PIPE_ISOCHRONOUS: {
-		int	n, len;
 
 		if (urb->number_of_packets <= 0)		    
 			return -EINVAL;
@@ -255,13 +252,9 @@ int usb_submit_urb(struct urb *urb, int mem_flags)
 			len = urb->iso_frame_desc [n].length;
 			if (len < 0 || len > max) 
 				return -EMSGSIZE;
+			urb->iso_frame_desc [n].status = -EXDEV;
+			urb->iso_frame_desc [n].actual_length = 0;
 		}
-
-		}
-		break;
-	case PIPE_INTERRUPT:
-		if (urb->transfer_buffer_length > max)
-			return -EMSGSIZE;
 	}
 
 	/* the I/O buffer must be mapped/unmapped, except when length=0 */

drivers/usb/core/usb.c

@@ -124,6 +124,8 @@ int usb_device_remove(struct device *dev)
 	if (driver->owner) {
 		m = try_inc_mod_count(driver->owner);
 		if (m == 0) {
+			// FIXME this happens even when we just rmmod
+			// drivers that aren't in active use... 
 			err("Dieing driver still bound to device.\n");
 			return -EIO;
 		}
@@ -1096,6 +1098,8 @@ int usb_new_device(struct usb_device *dev, struct device *parent)
  * avoid behaviors like using "DMA bounce buffers", or tying down I/O mapping
  * hardware for long idle periods.  The implementation varies between
  * platforms, depending on details of how DMA will work to this device.
+ * Using these buffers also helps prevent cacheline sharing problems on
+ * architectures where CPU caches are not DMA-coherent.
  *
  * When the buffer is no longer used, free it with usb_buffer_free().
  */

drivers/usb/host/ohci-hcd.c

@@ -193,12 +193,6 @@ static int ohci_urb_enqueue (
 			break;
 		case PIPE_ISOCHRONOUS: /* number of packets from URB */
 			size = urb->number_of_packets;
-			if (size <= 0)
-				return -EINVAL;
-			for (i = 0; i < urb->number_of_packets; i++) {
-  				urb->iso_frame_desc [i].actual_length = 0;
-  				urb->iso_frame_desc [i].status = -EXDEV;
-  			}
 			break;
 	}
 

include/linux/usb.h

@@ -452,9 +452,9 @@ static inline int usb_make_path (struct usb_device *dev, char *buf, size_t size)
  * User mode code can read these tables to choose which modules to load.
  * Declare the table as a MODULE_DEVICE_TABLE.
  *
- * The third probe() parameter will point to a matching entry from this
- * table.  (Null value reserved.)  Use the driver_data field for each
- * match to hold information tied to that match:  device quirks, etc.
+ * A probe() parameter will point to a matching entry from this table.
+ * Use the driver_info field for each match to hold information tied
+ * to that match:  device quirks, etc.
  *
  * Terminate the driver's table with an all-zeroes entry.
  * Use the flag values to control which fields are compared.
@@ -604,17 +604,14 @@ struct usb_device_id {
  * @name: The driver name should be unique among USB drivers,
  *	and should normally be the same as the module name.
  * @probe: Called to see if the driver is willing to manage a particular
- *	interface on a device.  The probe routine returns a handle that 
- *	will later be provided to disconnect(), or a null pointer to
- *	indicate that the driver will not handle the interface.
- *	The handle is normally a pointer to driver-specific data.
- *	If the probe() routine needs to access the interface
- *	structure itself, use usb_ifnum_to_if() to make sure it's using
- *	the right one.
+ *	interface on a device.  If it is, probe returns zero and uses
+ *	dev_set_drvdata() to associate driver-specific data with the
+ *	interface.  It may also use usb_set_interface() to specify the
+ *	appropriate altsetting.  If unwilling to manage the interface,
+ *	return a negative errno value.
  * @disconnect: Called when the interface is no longer accessible, usually
- *	because its device has been (or is being) disconnected.  The
- *	handle passed is what was returned by probe(), or was provided
- *	to usb_driver_claim_interface().
+ *	because its device has been (or is being) disconnected or the
+ *	driver module is being unloaded.
  * @ioctl: Used for drivers that want to talk to userspace through
  *	the "usbfs" filesystem.  This lets devices provide ways to
  *	expose information to user space regardless of where they
@@ -648,7 +645,7 @@ struct usb_driver {
 
 	void (*disconnect) (struct usb_interface *intf);
 
-	int (*ioctl) (struct usb_device *dev, unsigned int code, void *buf);
+	int (*ioctl) (struct usb_interface *intf, unsigned int code, void *buf);
 
 	const struct usb_device_id *id_table;
 

include/linux/usbdevice_fs.h

@@ -108,7 +108,7 @@ struct usbdevfs_urb {
 	struct usbdevfs_iso_packet_desc iso_frame_desc[0];
 };
 
-/* ioctls for talking to drivers in the usbcore module: */
+/* ioctls for talking directly to drivers */
 struct usbdevfs_ioctl {
 	int	ifno;		/* interface 0..N ; negative numbers reserved */
 	int	ioctl_code;	/* MUST encode size + direction of data so the