From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261796AbVGEKU5 (ORCPT ); Tue, 5 Jul 2005 06:20:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261778AbVGEKU4 (ORCPT ); Tue, 5 Jul 2005 06:20:56 -0400 Received: from mx1.redhat.com ([66.187.233.31]:6538 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S261796AbVGEKT0 (ORCPT ); Tue, 5 Jul 2005 06:19:26 -0400 Date: Tue, 05 Jul 2005 19:12:21 +0900 (JST) Message-Id: <20050705.191221.92572119.jet@gyve.org> To: linux-usb-devel@lists.sourceforge.net Cc: linux-kernel@vger.kernel.org Subject: [PATCH] Avoid to use kmalloc in usb/core/message.c From: Masatake YAMATO X-Mailer: Mew version 4.2 on Emacs 22.0.50 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org In some functions in drivers/usb/core/message.c kmalloc is used to allocate fix size of memory chunks; and the chunks is freed at the end of each functions. The sizes are not so large: 8(struct usb_ctrlrequest), 18(struct usb_device_descriptor), and 2(u16) bytes. I wonder why the invocations of kmalloc are needed in these functions. Following patch is for avoiding invocations of kmalloc. Instead stacks are used. The patch is generated by co-diff against rsync://kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git Signed-off-by: Masatake YAMATO Index: drivers/usb/core/message.c =================================================================== --- 6f51e67e4a433ee0ff866a6ac18a4bce798fe0c7/drivers/usb/core/message.c (mode:100644) +++ uncommitted/drivers/usb/core/message.c (mode:100644) @@ -142,11 +142,9 @@ int usb_control_msg(struct usb_device *dev, unsigned int pipe, __u8 request, __u8 requesttype, __u16 value, __u16 index, void *data, __u16 size, int timeout) { - struct usb_ctrlrequest *dr = kmalloc(sizeof(struct usb_ctrlrequest), GFP_NOIO); + struct usb_ctrlrequest dr_rec; + struct usb_ctrlrequest *dr = &dr_rec; int ret; - - if (!dr) - return -ENOMEM; dr->bRequestType= requesttype; dr->bRequest = request; @@ -158,7 +156,6 @@ ret = usb_internal_control_msg(dev, pipe, dr, data, size, timeout); - kfree(dr); return ret; } @@ -794,19 +791,17 @@ */ int usb_get_device_descriptor(struct usb_device *dev, unsigned int size) { + struct usb_device_descriptor desc_rec; struct usb_device_descriptor *desc; int ret; if (size > sizeof(*desc)) return -EINVAL; - desc = kmalloc(sizeof(*desc), GFP_NOIO); - if (!desc) - return -ENOMEM; + desc = &desc_rec; ret = usb_get_descriptor(dev, USB_DT_DEVICE, 0, desc, size); if (ret >= 0) memcpy(&dev->descriptor, desc, size); - kfree(desc); return ret; } @@ -835,17 +830,13 @@ int usb_get_status(struct usb_device *dev, int type, int target, void *data) { int ret; - u16 *status = kmalloc(sizeof(*status), GFP_KERNEL); - - if (!status) - return -ENOMEM; + u16 status; ret = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), - USB_REQ_GET_STATUS, USB_DIR_IN | type, 0, target, status, - sizeof(*status), USB_CTRL_GET_TIMEOUT); + USB_REQ_GET_STATUS, USB_DIR_IN | type, 0, target, &status, + sizeof(status), USB_CTRL_GET_TIMEOUT); - *(u16 *)data = *status; - kfree(status); + *(u16 *)data = status; return ret; }