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[PATCH] USB: optimise devio.c::usbdev_read

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

Signed-off-by: Oliver Neukum <oliver@neukum.name>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Oliver Neukum
2006-01-06 21:24:25 +01:00
committed by Greg Kroah-Hartman
parent 60f780528f
commit 8781ba0aa9
1 changed files with 8 additions and 13 deletions
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21
drivers/usb/core/devio.c
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@@ -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)) { if (pos < sizeof(struct usb_device_descriptor)) {
struct usb_device_descriptor *desc = kmalloc(sizeof(*desc), GFP_KERNEL); struct usb_device_descriptor temp_desc ; /* 18 bytes - fits on the stack */
if (!desc) {
ret = -ENOMEM; memcpy(&temp_desc, &dev->descriptor, sizeof(dev->descriptor));
goto err; le16_to_cpus(&temp_desc->bcdUSB);
} le16_to_cpus(&temp_desc->idVendor);
memcpy(desc, &dev->descriptor, sizeof(dev->descriptor)); le16_to_cpus(&temp_desc->idProduct);
le16_to_cpus(&desc->bcdUSB); le16_to_cpus(&temp_desc->bcdDevice);
le16_to_cpus(&desc->idVendor);
le16_to_cpus(&desc->idProduct);
le16_to_cpus(&desc->bcdDevice);
len = sizeof(struct usb_device_descriptor) - pos; len = sizeof(struct usb_device_descriptor) - pos;
if (len > nbytes) if (len > nbytes)
len = nbytes; len = nbytes;
if (copy_to_user(buf, ((char *)desc) + pos, len)) { if (copy_to_user(buf, ((char *)&temp_desc) + pos, len)) {
kfree(desc);
ret = -EFAULT; ret = -EFAULT;
goto err; goto err;
} }
kfree(desc);
*ppos += len; *ppos += len;
buf += len; buf += len;