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 X-Spam-Level: X-Spam-Status: No, score=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EFC47C4708B for ; Thu, 27 May 2021 20:16:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D06B961157 for ; Thu, 27 May 2021 20:16:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235539AbhE0US3 (ORCPT ); Thu, 27 May 2021 16:18:29 -0400 Received: from mail-ej1-f53.google.com ([209.85.218.53]:40898 "EHLO mail-ej1-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235519AbhE0US3 (ORCPT ); Thu, 27 May 2021 16:18:29 -0400 Received: by mail-ej1-f53.google.com with SMTP id jt22so2008549ejb.7 for ; Thu, 27 May 2021 13:16:55 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=yNxzDq2xY8dnUJ64MvViy+wB2IKXRy1JRa7aGjaRnQE=; b=eMLe8t2Xkp4hytqqo0+SLkrHpodnAlym7au7CcBHvcJysgAym3JL4Gr+PfSDcK7WPI +HKpMyJfSA00lH7PkqmiO50zGAHpbTTGPHT0J0Ep09hWdSxv1ZJm/qInVE8kU/qLGrFt 42yCNhfSumRFRsCRghuNlpld5XkPcoiwXXUXcF0Dhm3FKJjoJtqiFaxX4ViciHAV6QgN hhEXwXYTu9Tgb6Q/E4G4DVWWGzvFruiQ2dYzkZkPc1f3KgJZ2Tg3VnEgqW+AcAIRm37T Hz/f5E78Yu36ReyGzmMfpn46svXjsOfbGUquzJxqlhjltUnnIiSvuVk5D/FtyYTUcPOH ie8Q== X-Gm-Message-State: AOAM531uTh01vC8oE2dYi02DwMqdR0T0vpHnQ1JX2g5n6cEUSg9dS6Kl 39EPxFgi5mm0klgXXK65mUY= X-Google-Smtp-Source: ABdhPJy9jQFm2yS6uLlChglhd6jwpJ0rS0ZGrwwJUr97ehv8QsKDuJeuhso7++smmeegqRbQ1elJYg== X-Received: by 2002:a17:907:98a9:: with SMTP id ju9mr5663966ejc.257.1622146614847; Thu, 27 May 2021 13:16:54 -0700 (PDT) Received: from workstation.lan ([95.155.85.46]) by smtp.gmail.com with ESMTPSA id o64sm492739eda.83.2021.05.27.13.16.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 27 May 2021 13:16:54 -0700 (PDT) From: =?UTF-8?q?Krzysztof=20Wilczy=C5=84ski?= To: Bjorn Helgaas Cc: Logan Gunthorpe , Joe Perches , "Oliver O'Halloran" , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Tyrel Datwyler , Russell Currey , Kurt Schwemmer , Vidya Sagar , Xiongfeng Wang , linux-pci@vger.kernel.org Subject: [PATCH v5 3/5] PCI/sysfs: Fix trailing newline handling of resource_alignment_param Date: Thu, 27 May 2021 20:16:48 +0000 Message-Id: <20210527201650.221944-3-kw@linux.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210527201650.221944-1-kw@linux.com> References: <20210527201650.221944-1-kw@linux.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org The value of the "resource_alignment" can be specified using a kernel command-line argument (using the "pci=resource_alignment=") or through the corresponding sysfs object under the /sys/bus/pci path. Currently, when the value is set via the kernel command-line argument, and then subsequently accessed through sysfs object, the value read back will not be correct, as per: # grep -oE 'pci=resource_alignment.+' /proc/cmdline pci=resource_alignment=20@00:1f.2 # cat /sys/bus/pci/resource_alignment 20@00:1f. This is also true when the value is set through the sysfs object, but the trailing newline has not been included, as per: # echo -n 20@00:1f.2 > /sys/bus/pci/resource_alignment # cat /sys/bus/pci/resource_alignment 20@00:1f. When the value set through the sysfs object includes the trailing newline, then reading it back will work as intended, as per: # echo 20@00:1f.2 > /sys/bus/pci/resource_alignment # cat /sys/bus/pci/resource_alignment 20@00:1f.2 To fix this inconsistency, append a trailing newline in the show() function and strip the trailing line in the store() function if one is present. Also, allow for the value previously set using either a command-line argument or through the sysfs object to be cleared at run-time. Fixes: e499081da1a2 ("PCI: Force trailing new line to resource_alignment_param in sysfs") Signed-off-by: Krzysztof Wilczyński Reviewed-by: Logan Gunthorpe --- Changes in v2: None. Changes in v3: Added Logan Gunthorpe's "Reviewed-by". Changes in v4: None. Changes in v5: Added check to ensure that there is an extra space left in the buffer for the newline character, assuming that it might be provided. drivers/pci/pci.c | 34 ++++++++++++++++++++-------------- 1 file changed, 20 insertions(+), 14 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 5ed316ea5831..b46445a49543 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -6439,34 +6439,40 @@ static ssize_t resource_alignment_show(struct bus_type *bus, char *buf) spin_lock(&resource_alignment_lock); if (resource_alignment_param) - count = sysfs_emit(buf, "%s", resource_alignment_param); + count = sysfs_emit(buf, "%s\n", resource_alignment_param); spin_unlock(&resource_alignment_lock); - /* - * When set by the command line, resource_alignment_param will not - * have a trailing line feed, which is ugly. So conditionally add - * it here. - */ - if (count >= 2 && buf[count - 2] != '\n' && count < PAGE_SIZE - 1) { - buf[count - 1] = '\n'; - buf[count++] = 0; - } - return count; } static ssize_t resource_alignment_store(struct bus_type *bus, const char *buf, size_t count) { - char *param = kstrndup(buf, count, GFP_KERNEL); + char *param, *old, *end; + + if (count >= (PAGE_SIZE - 1)) + return -EINVAL; + param = kstrndup(buf, count, GFP_KERNEL); if (!param) return -ENOMEM; + end = strchr(param, '\n'); + if (end) + *end = '\0'; + spin_lock(&resource_alignment_lock); - kfree(resource_alignment_param); - resource_alignment_param = param; + old = resource_alignment_param; + if (strlen(param)) { + resource_alignment_param = param; + } else { + kfree(resource_alignment_param); + resource_alignment_param = NULL; + } spin_unlock(&resource_alignment_lock); + + kfree(old); + return count; } -- 2.31.1