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[2620:137:e000::1:20]) by mx.google.com with ESMTP id k21-20020aa7c395000000b004ad79751752si6132815edq.645.2023.02.26.09.42.14; Sun, 26 Feb 2023 09:42:36 -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=b9UBNZ3n; 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 S229781AbjBZRbE (ORCPT + 99 others); Sun, 26 Feb 2023 12:31:04 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57016 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229379AbjBZRbC (ORCPT ); Sun, 26 Feb 2023 12:31:02 -0500 Received: from msg-4.mailo.com (msg-4.mailo.com [213.182.54.15]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4EF339EDA; Sun, 26 Feb 2023 09:31:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=mailo.com; s=mailo; t=1677432612; bh=kbszH9m85sjV1+wRhwLfMuDJ81RvA1n+6wdLTFkDGHo=; h=X-EA-Auth:Date:From:To:Cc:Subject:Message-ID:References: MIME-Version:Content-Type:In-Reply-To; b=b9UBNZ3njp8Q3JxreIHTwITHrQVDR5FqkhQQgBQI5MIM+qV1/s6YGDpcEcG1dY4FC +caKAGNEmnVgLOp1dOsLWwolhIIQlWDcmTsRLf5Jsn/amajpVnXTw6Q94/sZlWQ3or jZ4VmXylgjA8dicOsY3IIx4aevc2twnZv+UvBApo= Received: by b-4.in.mailobj.net [192.168.90.14] with ESMTP via ip-206.mailobj.net [213.182.55.206] Sun, 26 Feb 2023 18:30:12 +0100 (CET) X-EA-Auth: XhjWn0297xPJSHS7FHXDD0OmaaUOkOqIx9ectiF4tFqsu0nxWKVrOT/JDOqNFYoDmelxxAbqRdV2V6eLAfm1h82mL63nuXtZ Date: Sun, 26 Feb 2023 23:00:06 +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 v3 1/3] perf/x86/core: Use sysfs_emit() in show() callback function Message-ID: <4fa04945ae4b6ee35943da25c6b75dbcaeaf6af0.1677431992.git.drv@mailo.com> 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?1758916359246634924?= X-GMAIL-MSGID: =?utf-8?q?1758916359246634924?= 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 v3: - Remove incorrect/erroneous change proposed. Feedback provided by Peter Zijlstra 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/core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index d096b04bf80e..87a7f0cd77fd 100644 --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -2544,7 +2544,7 @@ static ssize_t get_attr_rdpmc(struct device *cdev, struct device_attribute *attr, char *buf) { - return snprintf(buf, 40, "%d\n", x86_pmu.attr_rdpmc); + return sysfs_emit(buf, "%d\n", x86_pmu.attr_rdpmc); } static ssize_t set_attr_rdpmc(struct device *cdev, @@ -2602,7 +2602,7 @@ static ssize_t max_precise_show(struct device *cdev, struct device_attribute *attr, char *buf) { - return snprintf(buf, PAGE_SIZE, "%d\n", x86_pmu_max_precise()); + return sysfs_emit(buf, "%d\n", x86_pmu_max_precise()); } static DEVICE_ATTR_RO(max_precise); From patchwork Sun Feb 26 17:30:56 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: 61651 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a5d:5915:0:0:0:0:0 with SMTP id v21csp2038175wrd; Sun, 26 Feb 2023 09:46:08 -0800 (PST) X-Google-Smtp-Source: AK7set9Q/DJNlxUtG9+yCQIg038A7akm7A6o314zSJOmrWVPMIn16UQrzNL1W69moPtyR1qkG7F0 X-Received: by 2002:a05:6402:35d0:b0:4ad:6f56:a362 with SMTP id z16-20020a05640235d000b004ad6f56a362mr26641859edc.4.1677433568467; Sun, 26 Feb 2023 09:46:08 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1677433568; cv=none; d=google.com; s=arc-20160816; b=hfZRHbhBSULZYqRLye6j2vc63v6G7xpp1HE+WgtdERKYceQK82/nxbxYWME8p4jS8+ caU6Ssk6xEvkQQAeOXt+LA7yqpjAE1TfwBlrWxDeMVHIf/b5nafqfQyZyzC7kpooNnqh cNr+Pqjis/g5cZrZTuvHcD+CW2KnmKzfquqHBX1yrVsTI21QMvr5vYr7Dc50WmwsTtYb 2CsQC4Zjey3t2/+v42dAmXIuF30EiqvFWs+O0BWtqAk2kuMhdFJ3L7uSwkKqJbuqkopM mpQN62EjWk+siN5zdqiicmfCrDPZf1h1HmrAJPEgtAYCyS4bf/gsF8JBNcCBw73lHgXI Gnmg== 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=EFTCJfw4arTuzmCWTUpDS67d/iZJYf3d1cAVZ7NWtwM=; b=mUQDxvd0W3Qp62XR5kQuHePfoYt7gnlbtXC91R3jvFFkBMrw6xrwXwMzYmX13yR7eS 6wR6VqIt1EC4S/TLPP8XjnGxWHB9nt7tLTO/qUBmmpxS5+3M8jdbN/gfvrP0dGUyWN8B Eq83q+8DG2SrRie/8hL5B1YrwfQaNHH7YRCHyMMBDtZwEAYKxetU8tIB8ukjlWZcC4PD MKdSMpuSVeBbOLAl02RkSbvNSDwNFALkyzYEfxRqDJIk6BPetocE6KEF0P76zk8KaqZP A6pDLo9PMRsh0cVn9O2/M3oospug9WdybzTPbsAHLIUf1FelIf3P47JCvLqig0zZvspg 3hPw== ARC-Authentication-Results: i=1; mx.google.com; dkim=fail header.i=@mailo.com header.s=mailo header.b=GFUPRG+U; 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. 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Peter Anvin" , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Saurabh Singh Sengar , Praveen Kumar , Deepak R Varma Subject: [PATCH v3 2/3] perf/x86/intel/pt: Use sysfs_emit() in show() callback function Message-ID: <75e2b1f55156d8341e722eb923c9304a13def2b2.1677431992.git.drv@mailo.com> 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?1758916581621342544?= X-GMAIL-MSGID: =?utf-8?q?1758916581621342544?= 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 v3: - None. 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/pt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c index 42a55794004a..d9e6d771b458 100644 --- a/arch/x86/events/intel/pt.c +++ b/arch/x86/events/intel/pt.c @@ -96,7 +96,7 @@ static ssize_t pt_cap_show(struct device *cdev, container_of(attr, struct dev_ext_attribute, attr); enum pt_capabilities cap = (long)ea->var; - return snprintf(buf, PAGE_SIZE, "%x\n", intel_pt_validate_hw_cap(cap)); + return sysfs_emit(buf, "%x\n", intel_pt_validate_hw_cap(cap)); } static struct attribute_group pt_cap_group __ro_after_init = { From patchwork Sun Feb 26 17:31:39 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: 61652 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a5d:5915:0:0:0:0:0 with SMTP id v21csp2040731wrd; Sun, 26 Feb 2023 09:54:39 -0800 (PST) X-Google-Smtp-Source: AK7set/xF0v1LkYY7RVuXPBqVsZOMwkt/wHMrSUTito7yKnWorKK7K4kEAFrfsvltt9Skicw7nXF X-Received: by 2002:a05:6a20:8f10:b0:cd:c79:50d9 with SMTP id b16-20020a056a208f1000b000cd0c7950d9mr3228223pzk.2.1677434079217; Sun, 26 Feb 2023 09:54:39 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1677434079; cv=none; d=google.com; s=arc-20160816; b=O5F+FjoYLxUVLQwjxnCPN86c7kl0BESBdcAwwzIO4og7SqhIEKBVWBk6nK0SdBTNk6 xEE1POvpypXh1hic85scglcD228jaoxAEICAh7l2mh+CYowHmnDaWSPLvyc6fr4jbmu8 Nsb9M9iU6HDdCKNSb1Dcu+d1ElqjZQAHBPCMvGqmCwG24haVBBc/eAlhHaJXDE7INFNP W37HoBIJmRUWKE+ncI9XhVNBf6cj0MS2UCNGtyOv1nUjeO+7UdSRI8mF8xhMWKGWEL86 qBOZUNJbZt4ltn/KR02d8PYItm+iYgBUELgW95aGCZNIclvf0QAc7f0zot69d+NxjHKr KRDA== 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=KnU1luM8N4F0/XqEW/usbsMSVGwlJrJbmog5gerj9lk=; b=W0TahrCmeYKlqb/WVYQBbxwibSGEXIuTcWGe15vHuqL/1o55bHCzw31q4+p52q+sHI SFPPF6EoP7hRFfH3jCN/NCrkPSnhwYaUHcRBmCcgpE7JZxBiD0qu5DsNU51PbuYltcpR a8KUKBkb5C08+Mz52tVHNVjxNcCn0QATSN9vhmhG589WtF52+Pho5Kj8rYhUT1y0ZJkj MNdVJDOmRmZOPZjAsYwA7YloXArc0vJ4C41mbh/NTOtaSmlWZDaq5LecOrfLywyapNAy 97hnTsISVT0x8cdd+B6WRCZ4tB2FuM1lCEHat1EZ4342MIYMwOhdfoJnQDqdnMUfa8RM HdWg== ARC-Authentication-Results: i=1; mx.google.com; dkim=fail header.i=@mailo.com header.s=mailo header.b=WWmwd75W; 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. 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Peter Anvin" , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Saurabh Singh Sengar , Praveen Kumar , Deepak R Varma Subject: [PATCH v3 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?1758917116676189160?= X-GMAIL-MSGID: =?utf-8?q?1758917116676189160?= 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 v3: - None. 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 9fce2d1247a7..75ab89ff3a0f 100644 --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -5387,7 +5387,7 @@ 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, @@ -5421,7 +5421,7 @@ 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); @@ -5437,7 +5437,7 @@ 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);