USB: Check bandwidth when switching alt settings.

Make the USB core check the bandwidth when switching from one
interface alternate setting to another.  Also check the bandwidth
when resetting a configuration (so that alt setting 0 is used).  If
this check fails, the device's state is unchanged.  If the device
refuses the new alt setting, re-instate the old alt setting in the
host controller hardware.

If a USB device doesn't have an alternate interface setting 0, install
the first alt setting in its descriptors when a new configuration is
requested, or the device is reset.

Add a mutex per root hub to protect bandwidth operations:
adding/reseting/changing configurations, and changing alternate interface
settings.  We want to ensure that the xHCI host controller and the USB
device are set up for the same configurations and alternate settings.
There are two (possibly three) steps to do this:

 1. The host controller needs to check that bandwidth is available for a
    different setting, by issuing and waiting for a configure endpoint
    command.
 2. Once that returns successfully, a control message is sent to the
    device.
 3. If that fails, the host controller must be notified through another
    configure endpoint command.

The mutex is used to make these three operations seem atomic, to prevent
another driver from using more bandwidth for a different device while
we're in the middle of these operations.

While we're touching the bandwidth code, rename usb_hcd_check_bandwidth()
to usb_hcd_alloc_bandwidth().  This function does more than just check
that the bandwidth change won't exceed the bus bandwidth; it actually
changes the bandwidth configuration in the xHCI host controller.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 62 insertions, 7 deletions

diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
index adb9c8ee0c1f..ed83f2b1d551 100644
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -1298,6 +1298,7 @@ int usb_set_interface(struct usb_device *dev, int interface, int alternate)
 {
 	struct usb_interface *iface;
 	struct usb_host_interface *alt;
+	struct usb_hcd *hcd = bus_to_hcd(dev->bus);
 	int ret;
 	int manual = 0;
 	unsigned int epaddr;
@@ -1320,6 +1321,18 @@ int usb_set_interface(struct usb_device *dev, int interface, int alternate)
 		return -EINVAL;
 	}
 
+	/* Make sure we have enough bandwidth for this alternate interface.
+	 * Remove the current alt setting and add the new alt setting.
+	 */
+	mutex_lock(&hcd->bandwidth_mutex);
+	ret = usb_hcd_alloc_bandwidth(dev, NULL, iface->cur_altsetting, alt);
+	if (ret < 0) {
+		dev_info(&dev->dev, "Not enough bandwidth for altsetting %d\n",
+				alternate);
+		mutex_unlock(&hcd->bandwidth_mutex);
+		return ret;
+	}
+
 	if (dev->quirks & USB_QUIRK_NO_SET_INTF)
 		ret = -EPIPE;
 	else
@@ -1335,8 +1348,13 @@ int usb_set_interface(struct usb_device *dev, int interface, int alternate)
 			"manual set_interface for iface %d, alt %d\n",
 			interface, alternate);
 		manual = 1;
-	} else if (ret < 0)
+	} else if (ret < 0) {
+		/* Re-instate the old alt setting */
+		usb_hcd_alloc_bandwidth(dev, NULL, alt, iface->cur_altsetting);
+		mutex_unlock(&hcd->bandwidth_mutex);
 		return ret;
+	}
+	mutex_unlock(&hcd->bandwidth_mutex);
 
 	/* FIXME drivers shouldn't need to replicate/bugfix the logic here
 	 * when they implement async or easily-killable versions of this or
@@ -1418,6 +1436,7 @@ int usb_reset_configuration(struct usb_device *dev)
 {
 	int			i, retval;
 	struct usb_host_config	*config;
+	struct usb_hcd *hcd = bus_to_hcd(dev->bus);
 
 	if (dev->state == USB_STATE_SUSPENDED)
 		return -EHOSTUNREACH;
@@ -1433,12 +1452,46 @@ int usb_reset_configuration(struct usb_device *dev)
 	}
 
 	config = dev->actconfig;
+	retval = 0;
+	mutex_lock(&hcd->bandwidth_mutex);
+	/* Make sure we have enough bandwidth for each alternate setting 0 */
+	for (i = 0; i < config->desc.bNumInterfaces; i++) {
+		struct usb_interface *intf = config->interface[i];
+		struct usb_host_interface *alt;
+
+		alt = usb_altnum_to_altsetting(intf, 0);
+		if (!alt)
+			alt = &intf->altsetting[0];
+		if (alt != intf->cur_altsetting)
+			retval = usb_hcd_alloc_bandwidth(dev, NULL,
+					intf->cur_altsetting, alt);
+		if (retval < 0)
+			break;
+	}
+	/* If not, reinstate the old alternate settings */
+	if (retval < 0) {
+reset_old_alts:
+		for (; i >= 0; i--) {
+			struct usb_interface *intf = config->interface[i];
+			struct usb_host_interface *alt;
+
+			alt = usb_altnum_to_altsetting(intf, 0);
+			if (!alt)
+				alt = &intf->altsetting[0];
+			if (alt != intf->cur_altsetting)
+				usb_hcd_alloc_bandwidth(dev, NULL,
+						alt, intf->cur_altsetting);
+		}
+		mutex_unlock(&hcd->bandwidth_mutex);
+		return retval;
+	}
 	retval = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
 			USB_REQ_SET_CONFIGURATION, 0,
 			config->desc.bConfigurationValue, 0,
 			NULL, 0, USB_CTRL_SET_TIMEOUT);
 	if (retval < 0)
-		return retval;
+		goto reset_old_alts;
+	mutex_unlock(&hcd->bandwidth_mutex);
 
 	/* re-init hc/hcd interface/endpoint state */
 	for (i = 0; i < config->desc.bNumInterfaces; i++) {
@@ -1647,6 +1700,7 @@ int usb_set_configuration(struct usb_device *dev, int configuration)
 	int i, ret;
 	struct usb_host_config *cp = NULL;
 	struct usb_interface **new_interfaces = NULL;
+	struct usb_hcd *hcd = bus_to_hcd(dev->bus);
 	int n, nintf;
 
 	if (dev->authorized == 0 || configuration == -1)
@@ -1716,12 +1770,11 @@ free_interfaces:
 	 * host controller will not allow submissions to dropped endpoints.  If
 	 * this call fails, the device state is unchanged.
 	 */
-	if (cp)
-		ret = usb_hcd_check_bandwidth(dev, cp, NULL);
-	else
-		ret = usb_hcd_check_bandwidth(dev, NULL, NULL);
+	mutex_lock(&hcd->bandwidth_mutex);
+	ret = usb_hcd_alloc_bandwidth(dev, cp, NULL, NULL);
 	if (ret < 0) {
 		usb_autosuspend_device(dev);
+		mutex_unlock(&hcd->bandwidth_mutex);
 		goto free_interfaces;
 	}
 
@@ -1747,10 +1800,12 @@ free_interfaces:
 	dev->actconfig = cp;
 	if (!cp) {
 		usb_set_device_state(dev, USB_STATE_ADDRESS);
-		usb_hcd_check_bandwidth(dev, NULL, NULL);
+		usb_hcd_alloc_bandwidth(dev, NULL, NULL, NULL);
 		usb_autosuspend_device(dev);
+		mutex_unlock(&hcd->bandwidth_mutex);
 		goto free_interfaces;
 	}
+	mutex_unlock(&hcd->bandwidth_mutex);
 	usb_set_device_state(dev, USB_STATE_CONFIGURED);
 
 	/* Initialize the new interface structures and the