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Commit 8781ba0a authored by Oliver Neukum's avatar Oliver Neukum Committed by Greg Kroah-Hartman
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[PATCH] USB: optimise devio.c::usbdev_read



this is a small optimisation. It is ridiculous to do a kmalloc for
18 bytes. This puts it onto the stack.

Signed-off-by: default avatarOliver Neukum <oliver@neukum.name>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 60f78052
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+8 −13
Original line number Diff line number Diff line
@@ -134,26 +134,21 @@ static ssize_t usbdev_read(struct file *file, char __user *buf, size_t nbytes, l
	}

	if (pos < sizeof(struct usb_device_descriptor)) {
		struct usb_device_descriptor *desc = kmalloc(sizeof(*desc), GFP_KERNEL);
		if (!desc) {
			ret = -ENOMEM;
			goto err;
		}
		memcpy(desc, &dev->descriptor, sizeof(dev->descriptor));
		le16_to_cpus(&desc->bcdUSB);
		le16_to_cpus(&desc->idVendor);
		le16_to_cpus(&desc->idProduct);
		le16_to_cpus(&desc->bcdDevice);
		struct usb_device_descriptor temp_desc ; /* 18 bytes - fits on the stack */

		memcpy(&temp_desc, &dev->descriptor, sizeof(dev->descriptor));
		le16_to_cpus(&temp_desc->bcdUSB);
		le16_to_cpus(&temp_desc->idVendor);
		le16_to_cpus(&temp_desc->idProduct);
		le16_to_cpus(&temp_desc->bcdDevice);

		len = sizeof(struct usb_device_descriptor) - pos;
		if (len > nbytes)
			len = nbytes;
		if (copy_to_user(buf, ((char *)desc) + pos, len)) {
			kfree(desc);
		if (copy_to_user(buf, ((char *)&temp_desc) + pos, len)) {
			ret = -EFAULT;
			goto err;
		}
		kfree(desc);

		*ppos += len;
		buf += len;