From 8781ba0aa9d9dd2870b75dba8d9a47e0f5a3f96a Mon Sep 17 00:00:00 2001
From: Oliver Neukum <oliver@neukum.org>
Date: Fri, 6 Jan 2006 21:24:25 +0100
Subject: [PATCH] [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: Oliver Neukum <oliver@neukum.name>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
drivers/usb/core/devio.c | 21 ++++++++-------------
1 file changed, 8 insertions(+), 13 deletions(-)
diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index 2b68998fe4b34f..d01bd77e7b1479 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -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;
--
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