From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932295AbdA3PRq (ORCPT ); Mon, 30 Jan 2017 10:17:46 -0500 Received: from mfb02-md.ns.itscom.net ([175.177.155.110]:45173 "EHLO mfb02-md.ns.itscom.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932212AbdA3PQ2 (ORCPT ); Mon, 30 Jan 2017 10:16:28 -0500 X-Greylist: delayed 472 seconds by postgrey-1.27 at vger.kernel.org; Mon, 30 Jan 2017 10:16:28 EST From: "J. R. Okajima" To: james.smart@broadcom.com cc: sagi@grimberg.me, james_p_freyensee@linux.intel.com, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org Subject: Re: [PATCH v4] add u64 number parser Date: Tue, 31 Jan 2017 00:08:00 +0900 Message-ID: <26045.1485788880@jrobl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello James, Your commit a317178 2016-12-06 parser: add u64 number parser was merged into v4.10-rc1. Good. I have a very similar function and used for a long time. Here I'd suggest you a tiny optimization based on my version. If you think another value is more apropriate as the size of an internal array, you can change it freely. J. R. Okajima commit 030361e78d327d9d89254dc3b320c092221c7cd0 Author: J. R. Okajima Date: Tue Jan 31 00:01:16 2017 +0900 parser: match_u64, short string optimization = When the given string is short enough, we can skip kmalloc/kfree. Signed-off-by: J. R. Okajima diff --git a/lib/parser.c b/lib/parser.c index 3278958..cfbc6ec 100644 --- a/lib/parser.c +++ b/lib/parser.c @@ -163,21 +163,25 @@ static int match_number(substring_t *s, int *result,= int base) */ static int match_u64int(substring_t *s, u64 *result, int base) { - char *buf; + char *buf, a[32]; int ret; u64 val; size_t len =3D s->to - s->from; = - buf =3D kmalloc(len + 1, GFP_KERNEL); - if (!buf) - return -ENOMEM; + buf =3D a; + if (len + 1 > sizeof(a)) { + buf =3D kmalloc(len + 1, GFP_KERNEL); + if (unlikely(!buf)) + return -ENOMEM; + } memcpy(buf, s->from, len); buf[len] =3D '\0'; = ret =3D kstrtoull(buf, base, &val); if (!ret) *result =3D val; - kfree(buf); + if (buf !=3D a) + kfree(buf); return ret; } =