USB: add all configs to the "descriptors" attribute (217a9081) · Commits · 戴 / test

This patch (as1094) changes the output of the "descriptors" binary attribute. Now it will contain the device descriptor followed by all the configuration descriptors, not just the descriptor for the current config. Userspace libraries want to have access to the kernel's cached descriptor information, so they can learn about device characteristics without having to wake up suspended devices. So far the only user of this attribute is the new libusb-1.0 library; thus changing its contents shouldn't cause any problems. This should be considered for 2.6.26, if for no other reason than to minimize the range of releases in which the attribute contains only the current config descriptor. Also, it doesn't hurt that the patch removes the device locking -- which was formerly needed in order to know for certain which config was indeed current. Signed-off-by:

Alan Stern <stern@rowland.harvard.edu> Signed-off-by:

Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/core/sysfs.c

+21 −23

Original line number	Diff line number	Diff line
		@@ -588,35 +588,33 @@ read_descriptors(struct kobject kobj, struct bin_attribute attr,
		container_of(kobj, struct device, kobj));
		size_t nleft = count;
		size_t srclen, n;
		int cfgno;
		void *src;

		usb_lock_device(udev);

		/* The binary attribute begins with the device descriptor */
		/* The binary attribute begins with the device descriptor.
		* Following that are the raw descriptor entries for all the
		* configurations (config plus subsidiary descriptors).
		*/
		for (cfgno = -1; cfgno < udev->descriptor.bNumConfigurations &&
		nleft > 0; ++cfgno) {
		if (cfgno < 0) {
		src = &udev->descriptor;
		srclen = sizeof(struct usb_device_descriptor);
		} else {
		src = udev->rawdescriptors[cfgno];
		srclen = __le16_to_cpu(udev->config[cfgno].desc.
		wTotalLength);
		}
		if (off < srclen) {
		n = min_t(size_t, nleft, srclen - off);
		memcpy(buf, off + (char *) &udev->descriptor, n);
		n = min(nleft, srclen - (size_t) off);
		memcpy(buf, src + off, n);
		nleft -= n;
		buf += n;
		off = 0;
		} else {
		off -= srclen;
		}

		/* Then follows the raw descriptor entry for the current
		* configuration (config plus subsidiary descriptors).
		*/
		if (udev->actconfig) {
		int cfgno = udev->actconfig - udev->config;

		srclen = __le16_to_cpu(udev->actconfig->desc.wTotalLength);
		if (off < srclen) {
		n = min_t(size_t, nleft, srclen - off);
		memcpy(buf, off + udev->rawdescriptors[cfgno], n);
		nleft -= n;
		}
		}
		usb_unlock_device(udev);
		return count - nleft;
		}

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