Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261186AbVCaI1Z (ORCPT ); Thu, 31 Mar 2005 03:27:25 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261174AbVCaI1Y (ORCPT ); Thu, 31 Mar 2005 03:27:24 -0500 Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:42392 "EHLO parcelfarce.linux.theplanet.co.uk") by vger.kernel.org with ESMTP id S261186AbVCaI06 (ORCPT ); Thu, 31 Mar 2005 03:26:58 -0500 Message-ID: <424BB443.1070508@pobox.com> Date: Thu, 31 Mar 2005 03:26:43 -0500 From: Jeff Garzik User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.6) Gecko/20050328 Fedora/1.7.6-1.2.5 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Yum Rayan CC: linux-kernel@vger.kernel.org Subject: Re: [PATCH] Reduce stack usage in time.c References: In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1670 Lines: 58 Yum Rayan wrote: > Attempt to reduce stack usage in time.c (linux-2.6.12-rc1-mm3). Stack > usage was noted using checkstack.pl. Specifically: > > Before patch > ------------ > sys_adjtimex - 128 > > After patch > ----------- > sys_adjtimex - none (register usage only) > > Signed-off-by: Yum Rayan > > --- a/kernel/time.c 2005-03-25 22:11:06.000000000 -0800 > +++ b/kernel/time.c 2005-03-30 16:59:51.000000000 -0800 > @@ -413,17 +413,27 @@ > > asmlinkage long sys_adjtimex(struct timex __user *txc_p) > { > - struct timex txc; /* Local copy of parameter */ > - int ret; > + struct timex *txc; /* Local copy of parameter */ > + int retval; > + > + txc = kmalloc(sizeof(struct timex), GFP_KERNEL); > + if (!txc) > + return -ENOMEM; > > /* Copy the user data space into the kernel copy > * structure. But bear in mind that the structures > * may change > */ > - if(copy_from_user(&txc, txc_p, sizeof(struct timex))) > - return -EFAULT; > - ret = do_adjtimex(&txc); > - return copy_to_user(txc_p, &txc, sizeof(struct timex)) ? -EFAULT : ret; > + if(copy_from_user(txc, txc_p, sizeof(struct timex))) { > + retval = -EFAULT; > + goto free_txc; > + } > + retval = do_adjtimex(txc); > + if (copy_to_user(txc_p, txc, sizeof(struct timex))) > + retval = -EFAULT; > +free_txc: It seems quite unhealthy to add a kmalloc(,GFP_KERNEL) allocation into a time-sensitive function. Jeff - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/