From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752114AbbALRNz (ORCPT ); Mon, 12 Jan 2015 12:13:55 -0500 Received: from smtprelay0061.hostedemail.com ([216.40.44.61]:46719 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751054AbbALRNy (ORCPT ); Mon, 12 Jan 2015 12:13:54 -0500 X-Session-Marker: 6A6F6540706572636865732E636F6D X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,joe@perches.com,:::::::::::::::::::,RULES_HIT:41:355:379:541:599:966:973:988:989:1260:1277:1311:1313:1314:1345:1359:1373:1437:1515:1516:1518:1534:1541:1593:1594:1711:1730:1747:1777:1792:2196:2198:2199:2200:2393:2559:2562:2828:3138:3139:3140:3141:3142:3352:3622:3865:3866:3867:3868:3870:3871:3872:4321:4385:5007:6261:7903:10004:10400:10848:11026:11232:11658:11914:12043:12296:12517:12519:12740:13069:13311:13357:21080,0,RBL:none,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fn,MSBL:0,DNSBL:none,Custom_rules:0:0:0 X-HE-Tag: leaf31_78ca9c6219c17 X-Filterd-Recvd-Size: 2128 Message-ID: <1421082828.9233.13.camel@perches.com> Subject: Re: [PATCH 1/5] mm/util: add kstrdup_const From: Joe Perches To: Andrzej Hajda Cc: linux-mm@kvack.org, Marek Szyprowski , Kyungmin Park , linux-kernel@vger.kernel.org, andi@firstfloor.org, andi@lisas.de, Mike Turquette , Alexander Viro , Andrew Morton Date: Mon, 12 Jan 2015 09:13:48 -0800 In-Reply-To: <1421054323-14430-2-git-send-email-a.hajda@samsung.com> References: <1421054323-14430-1-git-send-email-a.hajda@samsung.com> <1421054323-14430-2-git-send-email-a.hajda@samsung.com> Content-Type: text/plain; charset="ISO-8859-1" X-Mailer: Evolution 3.12.7-0ubuntu1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2015-01-12 at 10:18 +0100, Andrzej Hajda wrote: > The patch adds alternative version of kstrdup which returns pointer > to constant char array. The function checks if input string is in > persistent and read-only memory section, if yes it returns the input string, > otherwise it fallbacks to kstrdup. > kstrdup_const is accompanied by kfree_const performing conditional memory > deallocation of the string. trivia: > diff --git a/mm/util.c b/mm/util.c [] > +void kfree_const(const void *x) > +{ > + if (!is_kernel_rodata((unsigned long)x)) > + kfree(x); > +} > +EXPORT_SYMBOL(kfree_const); [] > +const char *kstrdup_const(const char *s, gfp_t gfp) > +{ > + if (is_kernel_rodata((unsigned long)s)) > + return s; > + > + return kstrdup(s, gfp); > +} > +EXPORT_SYMBOL(kstrdup_const); I think it'd be nicer if these used the same form even if it's a vertical line or 2 longer void kfree_const(const void *x) { if (is_kernel_rodata((unsigned long)x)) return; kfree(x); }