Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261228AbVCaJdE (ORCPT ); Thu, 31 Mar 2005 04:33:04 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261299AbVCaJa5 (ORCPT ); Thu, 31 Mar 2005 04:30:57 -0500 Received: from 168.imtp.Ilyichevsk.Odessa.UA ([195.66.192.168]:9476 "HELO port.imtp.ilyichevsk.odessa.ua") by vger.kernel.org with SMTP id S261262AbVCaJ1e (ORCPT ); Thu, 31 Mar 2005 04:27:34 -0500 From: Denis Vlasenko To: Jeff Garzik , Yum Rayan Subject: Re: [PATCH] Reduce stack usage in time.c Date: Thu, 31 Mar 2005 12:26:58 +0300 User-Agent: KMail/1.5.4 Cc: linux-kernel@vger.kernel.org References: <424BB443.1070508@pobox.com> In-Reply-To: <424BB443.1070508@pobox.com> MIME-Version: 1.0 Content-Type: text/plain; charset="koi8-r" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200503311226.58037.vda@ilport.com.ua> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1789 Lines: 57 On Thursday 31 March 2005 11:26, Jeff Garzik wrote: > 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: Is this a syscall? Is it ever called from some deeply nested kernel function? -- vda - 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/