From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755749Ab3ILAE1 (ORCPT ); Wed, 11 Sep 2013 20:04:27 -0400 Received: from smtprelay0227.hostedemail.com ([216.40.44.227]:49589 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750899Ab3ILAEZ (ORCPT ); Wed, 11 Sep 2013 20:04:25 -0400 X-Session-Marker: 6A6F6540706572636865732E636F6D X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,joe@perches.com,:::::::::::::::::::::::::::::::::::::::,RULES_HIT:41:355:379:541:599:960:973 X-HE-Tag: mouth25_25a9c59c2b560 X-Filterd-Recvd-Size: 2776 Message-ID: <1378944257.4714.45.camel@joe-AO722> Subject: Re: [RFC PATCH] vsnprintf: Remove use of %n and convert existing uses From: Joe Perches To: Tetsuo Handa Cc: linux-kernel@vger.kernel.org, kosaki.motohiro@jp.fujitsu.com, keescook@chromium.org, fweisbec@gmail.com, dan.carpenter@oracle.com, devel@driverdev.osuosl.org, gregkh@linuxfoundation.org, tushar.behera@linaro.org, lidza.louina@gmail.com, davem@davemloft.net, kuznet@ms2.inr.ac.ru, jmorris@namei.org, yoshfuji@linux-ipv6.org, kaber@trash.net, courmisch@gmail.com, vyasevich@gmail.com, nhorman@tuxdriver.com, netdev@vger.kernel.org, linux-sctp@vger.kernel.org Date: Wed, 11 Sep 2013 17:04:17 -0700 In-Reply-To: <201309120840.HHE37542.OJMFFHSOQOtVFL@I-love.SAKURA.ne.jp> References: <1378926562.4714.11.camel@joe-AO722> <1378928700.4714.17.camel@joe-AO722> <1378941761.4714.37.camel@joe-AO722> <201309120840.HHE37542.OJMFFHSOQOtVFL@I-love.SAKURA.ne.jp> Content-Type: text/plain; charset="ISO-8859-1" X-Mailer: Evolution 3.6.4-0ubuntu1 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 Thu, 2013-09-12 at 08:40 +0900, Tetsuo Handa wrote: > Joe Perches wrote: > > - seq_printf(m, "%s%d%n", con->name, con->index, &len); > > + len = seq_printf(m, "%s%d", con->name, con->index); > > Isn't len always 0 or -1 ? Right. Well you're no fun... These uses would seem broken anyway because the seq_printf isn't itself tested for correctness. Hmm. Also, there's a large amount of code that appears to do calculations with pos or len like: pos += seq_printf(handle, fmt. ...) There are very few that seem to use it correctly like netfilter. $ grep -rP --include=*.[ch] "^[ \t]*\S[ \t\S]*\bseq_[v]?printf\b" * Suggestions? > int seq_vprintf(struct seq_file *m, const char *f, va_list args) > { > int len; > > if (m->count < m->size) { > len = vsnprintf(m->buf + m->count, m->size - m->count, f, args); > if (m->count + len < m->size) { > m->count += len; > return 0; > } > } > seq_set_overflow(m); > return -1; > } > EXPORT_SYMBOL(seq_vprintf); > > int seq_printf(struct seq_file *m, const char *f, ...) > { > int ret; > va_list args; > > va_start(args, f); > ret = seq_vprintf(m, f, args); > va_end(args); > > return ret; > } > EXPORT_SYMBOL(seq_printf);