From patchwork Tue Feb 21 14:07:33 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Deepak R Varma X-Patchwork-Id: 60109 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a5d:5915:0:0:0:0:0 with SMTP id v21csp38757wrd; Tue, 21 Feb 2023 06:29:24 -0800 (PST) X-Google-Smtp-Source: AK7set/eblgFMzcWdjUxGnId7lAXZ7Ewxm/Kr81xN/v7twrEgABIkKRJzVLk7x4KGsbRjh3BCOn6 X-Received: by 2002:a17:906:57c6:b0:8b1:fc1a:7d19 with SMTP id u6-20020a17090657c600b008b1fc1a7d19mr14770123ejr.3.1676989764614; Tue, 21 Feb 2023 06:29:24 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1676989764; cv=none; d=google.com; s=arc-20160816; b=Zr2dwvC+3ThlQAdShMP6woEQQGBkG6uRZzH7IxU5qyA3cP4kxUd2cCq5ZRS6gsxbOX WWAvzYmkP76k+poyoLIDfKnEoO0D7TNwfX5rrYpkvTPiVk9l7VvSSMFlB5A9cCVPB3RI iaZF5J9vrCLGjHYrPfxmg0ORHcCXB001Rr5/G9AjwjvpBEOHZE8lojrFr3jj6QYWRWri TNX7x6dajexNptA+dU4fjP5ozfJLjdV48MPTid0THvxIpWKpe9GnuKGyoADS5q3+rKTj R+wDsk/KyFhszSK7DxiJmWVXMpjLzQtDe6YVpNPHmV0QdoZToTlLe9NFLETRoKeKW8dS mfQA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:in-reply-to:content-disposition:mime-version :references:message-id:subject:cc:to:from:date:dkim-signature; bh=1IueYwST8+uFopStSTJwEWVD21VMPQXRRbeA1rPC4u4=; b=gFRz3E+vVNfzUdSZZh69dr8U9qGyL30kBPFMf+PXIf+pnmnrHLHgBqSTXxyKacDGUn eqHezwW8NrqsptsAQcA1LoIHWgtJO7NZKG9CgYrU8ww0jK0xGjiVXfpfkFtRSnBthYkK tFOpsRjj7ciQVO854S9XYQwwIa2gqOabafAv4mm4cg7otEquoy2l251qIjZphOXHPW9b VV05vZhNmWmW99iau+AjBjDpd6Pa6JYg3e3aPG1KsLC3inV0nso3X0r2s5EL/e0AR3Bw mdPllSRTs1GfWlzV9ibn8WR8DUdwU+rGZgBBQyNiBvxH39zkdaya2D5HLCwDlRg7i4zz hlKA== ARC-Authentication-Results: i=1; mx.google.com; dkim=fail header.i=@mailo.com header.s=mailo header.b=jJMAjZ+w; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=mailo.com Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id ew6-20020a170907950600b008c9eb8758desi8869455ejc.915.2023.02.21.06.29.01; Tue, 21 Feb 2023 06:29:24 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=fail header.i=@mailo.com header.s=mailo header.b=jJMAjZ+w; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=mailo.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233887AbjBUOIX (ORCPT + 99 others); Tue, 21 Feb 2023 09:08:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60400 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234307AbjBUOIU (ORCPT ); Tue, 21 Feb 2023 09:08:20 -0500 Received: from msg-2.mailo.com (msg-2.mailo.com [213.182.54.12]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2CF72DBF0; Tue, 21 Feb 2023 06:08:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=mailo.com; s=mailo; t=1676988458; bh=Rbss0jxu2oGKjdOiKMyt4uKTBzrOuv6xJ/DDTtxIAQM=; h=X-EA-Auth:Date:From:To:Cc:Subject:Message-ID:References: MIME-Version:Content-Type:In-Reply-To; b=jJMAjZ+wRXfZFrYdt+Xcn/ezo/9xrp/LwdbJoKl+AwbZm80cZgUsaDEbAWPJRxOBU HIM6ejsCz0X04GFUTgdxcvWy6IG+M2/nxMprwhgGlNT/3F8TJ3VgNxQBi54VdouWI9 6sBCN1q9IMevCHLOoKiHI+3JiSMc2d3w3VrlkmXc= Received: by b-4.in.mailobj.net [192.168.90.14] with ESMTP via ip-206.mailobj.net [213.182.55.206] Tue, 21 Feb 2023 15:07:38 +0100 (CET) X-EA-Auth: vqvzvLOiwMJVZ0nf4zmrjP3ujrlYSnChDzDG2lu6ZTVMp0oV+9+mMIgP7QH2LsPs0i4s9VN9g+YYQSaiMUmcCpK/f2s81Znu Date: Tue, 21 Feb 2023 19:37:33 +0530 From: Deepak R Varma To: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Thomas Gleixner , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Saurabh Singh Sengar , Praveen Kumar , Deepak R Varma Subject: [PATCH v2 3/3] perf/x86/intel: Use sysfs_emit() in show() callback function Message-ID: References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1758451218943641338?= X-GMAIL-MSGID: =?utf-8?q?1758451218943641338?= As per C99 standard, snprintf() returns the number of bytes that would be encoded in the destination buffer when it is sufficiently large. This return value may be different from what the caller is expecting and hence may lead to potential errors in the program. Kernel release 2.6.2 introduced scnprintf() & vscnprintf() which precisely return the actual bytes encoded into the destination buffer. For the sysfs attribute show() callback functions, which returns the number of bytes to the user space, a more recent recommendation is to use sysfs_emit() or sysfs_emit_at() instead of sprintf() family of functions. This is recorded in the Documentation/filesystems/sysfs.rst Kernel documentation file. Issue identified using the coccinelle device_attr_show.cocci script. Signed-off-by: Deepak R Varma --- Changes in v2: - Revise patch log message to include details on the potential issues with current implementation and how the proposal is a better solution. Feedback provided by Peter Zijlstra arch/x86/events/intel/core.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c index bafdc2be479a..8fb1225123ef 100644 --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -5273,7 +5273,7 @@ static ssize_t show_sysctl_tfa(struct device *cdev, struct device_attribute *attr, char *buf) { - return snprintf(buf, 40, "%d\n", allow_tsx_force_abort); + return sysfs_emit(buf, "%d\n", allow_tsx_force_abort); } static ssize_t set_sysctl_tfa(struct device *cdev, @@ -5307,7 +5307,7 @@ static ssize_t branches_show(struct device *cdev, struct device_attribute *attr, char *buf) { - return snprintf(buf, PAGE_SIZE, "%d\n", x86_pmu.lbr_nr); + return sysfs_emit(buf, "%d\n", x86_pmu.lbr_nr); } static DEVICE_ATTR_RO(branches); @@ -5323,7 +5323,7 @@ static ssize_t pmu_name_show(struct device *cdev, struct device_attribute *attr, char *buf) { - return snprintf(buf, PAGE_SIZE, "%s\n", pmu_name_str); + return sysfs_emit(buf, "%s\n", pmu_name_str); } static DEVICE_ATTR_RO(pmu_name);