From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9B11DC32771 for ; Wed, 28 Sep 2022 09:38:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233567AbiI1JiT (ORCPT ); Wed, 28 Sep 2022 05:38:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47450 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229847AbiI1Jhp (ORCPT ); Wed, 28 Sep 2022 05:37:45 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id B7A38ED5FD for ; Wed, 28 Sep 2022 02:36:38 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 29C851063; Wed, 28 Sep 2022 02:35:54 -0700 (PDT) Received: from [10.57.33.30] (unknown [10.57.33.30]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 6DC9C3F792; Wed, 28 Sep 2022 02:35:46 -0700 (PDT) Message-ID: Date: Wed, 28 Sep 2022 10:35:44 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH 5/7] kernel/cpu: Convert snprintf() to scnprintf() Content-Language: en-GB To: Jules Irenge , tglx@linutronix.de Cc: sathyanarayanan.kuppuswamy@linux.intel.com, linux-kernel@vger.kernel.org, dave.hansen@linux.intel.com, ak@linux.intel.com, Jason@zx2c4.com References: From: Steven Price In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 26/09/2022 19:52, Jules Irenge wrote: > Coccinnelle reports a warning > Warning: Use scnprintf or sprintf > Adding to that, there has been a slow migration from snprintf to scnprintf. > This LWN article explains the rationale for this change > https: //lwn.net/Articles/69419/ > Ie. snprintf() returns what *would* be the resulting length, > while scnprintf() returns the actual length. > > Signed-off-by: Jules Irenge Using sysfs_emit() would be even better in this case, although it's slightly different because it outputs a maximum of PAGE_SIZE rather than PAGE_SIZE - 2 bytes. But I can't see any reason for that "- 2" - it appears to have been added when the sysfs entry was added by Thomas Gleixner in commit 05736e4ac13c ("cpu/hotplug: Provide knobs to control SMT") but I don't see any justification for it. Steve > --- > kernel/cpu.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/kernel/cpu.c b/kernel/cpu.c > index bbad5e375d3b..f358d89c9580 100644 > --- a/kernel/cpu.c > +++ b/kernel/cpu.c > @@ -2512,7 +2512,7 @@ static ssize_t control_show(struct device *dev, > { > const char *state = smt_states[cpu_smt_control]; > > - return snprintf(buf, PAGE_SIZE - 2, "%s\n", state); > + return scnprintf(buf, PAGE_SIZE - 2, "%s\n", state); > } > > static ssize_t control_store(struct device *dev, struct device_attribute *attr, > @@ -2525,7 +2525,7 @@ static DEVICE_ATTR_RW(control); > static ssize_t active_show(struct device *dev, > struct device_attribute *attr, char *buf) > { > - return snprintf(buf, PAGE_SIZE - 2, "%d\n", sched_smt_active()); > + return scnprintf(buf, PAGE_SIZE - 2, "%d\n", sched_smt_active()); > } > static DEVICE_ATTR_RO(active); >