From patchwork Sat Nov 19 08:32:47 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ashok Raj X-Patchwork-Id: 9437935 X-Patchwork-Delegate: bhelgaas@google.com Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id AB14660238 for ; Sat, 19 Nov 2016 08:33:17 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9C5A129911 for ; Sat, 19 Nov 2016 08:33:17 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8C7C629962; Sat, 19 Nov 2016 08:33:17 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0FB17298F3 for ; Sat, 19 Nov 2016 08:33:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752821AbcKSIc4 (ORCPT ); Sat, 19 Nov 2016 03:32:56 -0500 Received: from mga06.intel.com ([134.134.136.31]:20360 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752695AbcKSIcx (ORCPT ); Sat, 19 Nov 2016 03:32:53 -0500 Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by orsmga104.jf.intel.com with ESMTP; 19 Nov 2016 00:32:51 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.31,662,1473145200"; d="scan'208";a="33236250" Received: from otc-nc-03.jf.intel.com ([10.54.39.141]) by fmsmga006.fm.intel.com with ESMTP; 19 Nov 2016 00:32:51 -0800 From: Ashok Raj To: linux-pci@vger.kernel.org, Bjorn Helgaas Cc: Ashok Raj , Keith Busch , linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH 3/3] pciehp: Fix race condition handling surprise link-down Date: Sat, 19 Nov 2016 00:32:47 -0800 Message-Id: <1479544367-7195-4-git-send-email-ashok.raj@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1479544367-7195-1-git-send-email-ashok.raj@intel.com> References: <1479544367-7195-1-git-send-email-ashok.raj@intel.com> Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP A surprise link down may retrain very quickly, causing the same slot to generate a link up event before handling the link down completes. Since the link is active, the power off work queued from the first link down will cause a second down event when the power is disabled. The second down event should be ignored because the slot is already powering off; however, the "link up" event sets the slot state to POWERON before the event to handle this is enqueued, making the second down event believe it needs to do something. This creates a constant link up and down event cycle. This patch fixes that by setting the slot state only when the work to handle the power event is executing, protected by the hot plug mutex. Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org Signed-off-by: Ashok Raj Reviewed-by: Keith Busch --- drivers/pci/hotplug/pciehp_ctrl.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/pci/hotplug/pciehp_ctrl.c b/drivers/pci/hotplug/pciehp_ctrl.c index ec0b4c1..7ae068c 100644 --- a/drivers/pci/hotplug/pciehp_ctrl.c +++ b/drivers/pci/hotplug/pciehp_ctrl.c @@ -182,6 +182,7 @@ static void pciehp_power_thread(struct work_struct *work) switch (info->req) { case DISABLE_REQ: mutex_lock(&p_slot->hotplug_lock); + p_slot->state = POWEROFF_STATE; pciehp_disable_slot(p_slot); mutex_unlock(&p_slot->hotplug_lock); mutex_lock(&p_slot->lock); @@ -190,6 +191,7 @@ static void pciehp_power_thread(struct work_struct *work) break; case ENABLE_REQ: mutex_lock(&p_slot->hotplug_lock); + p_slot->state = POWERON_STATE; ret = pciehp_enable_slot(p_slot); mutex_unlock(&p_slot->hotplug_lock); if (ret) @@ -209,8 +211,6 @@ static void pciehp_queue_power_work(struct slot *p_slot, int req) { struct power_work_info *info; - p_slot->state = (req == ENABLE_REQ) ? POWERON_STATE : POWEROFF_STATE; - info = kmalloc(sizeof(*info), GFP_KERNEL); if (!info) { ctrl_err(p_slot->ctrl, "no memory to queue %s request\n",