From patchwork Fri Mar 26 10:56:19 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Adrian Hunter X-Patchwork-Id: 12166349 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=-16.8 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 141DBC433E2 for ; Fri, 26 Mar 2021 10:57:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D98B861A50 for ; Fri, 26 Mar 2021 10:57:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229986AbhCZK4r (ORCPT ); Fri, 26 Mar 2021 06:56:47 -0400 Received: from mga09.intel.com ([134.134.136.24]:2701 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229963AbhCZK4P (ORCPT ); Fri, 26 Mar 2021 06:56:15 -0400 IronPort-SDR: gAGv8KC/PN1OjQFwLNKhpSMBFTMPkTpvbkbCSlczm2gxTUUYlFgGUl6O/oHPJerszwdXPrWFyz AkyXzXGoGGEA== X-IronPort-AV: E=McAfee;i="6000,8403,9934"; a="191220953" X-IronPort-AV: E=Sophos;i="5.81,280,1610438400"; d="scan'208";a="191220953" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Mar 2021 03:56:15 -0700 IronPort-SDR: nSI2OFo0sWAKYJqNz0xXOPiqhkfcQMAUU5L08NK8tzxmRJ5e4ahVQRnFosmc++H3neH3xBLFRB XwkWC3sYVW/g== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.81,280,1610438400"; d="scan'208";a="409849762" Received: from ahunter-desktop.fi.intel.com ([10.237.72.174]) by fmsmga008.fm.intel.com with ESMTP; 26 Mar 2021 03:56:12 -0700 From: Adrian Hunter To: "Rafael J . Wysocki" Cc: linux-pm@vger.kernel.org, "Martin K . Petersen" , "James E . J . Bottomley" , linux-scsi@vger.kernel.org, Avri Altman , Bean Huo , Can Guo , Asutosh Das Subject: [PATCH 2/2] PM: runtime: Fix race getting/putting suppliers at probe Date: Fri, 26 Mar 2021 12:56:19 +0200 Message-Id: <20210326105619.27570-3-adrian.hunter@intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20210326105619.27570-1-adrian.hunter@intel.com> References: <20210326105619.27570-1-adrian.hunter@intel.com> Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki, Business Identity Code: 0357606 - 4, Domiciled in Helsinki Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org pm_runtime_put_suppliers() must not decrement rpm_active unless the consumer is suspended. That is because, otherwise, it could suspend suppliers for an active consumer. That can happen as follows: static int driver_probe_device(struct device_driver *drv, struct device *dev) { int ret = 0; if (!device_is_registered(dev)) return -ENODEV; dev->can_match = true; pr_debug("bus: '%s': %s: matched device %s with driver %s\n", drv->bus->name, __func__, dev_name(dev), drv->name); pm_runtime_get_suppliers(dev); if (dev->parent) pm_runtime_get_sync(dev->parent); At this point, dev can runtime suspend so rpm_put_suppliers() can run, rpm_active becomes 1 (the lowest value). pm_runtime_barrier(dev); if (initcall_debug) ret = really_probe_debug(dev, drv); else ret = really_probe(dev, drv); Probe callback can have runtime resumed dev, and then runtime put so dev is awaiting autosuspend, but rpm_active is 2. pm_request_idle(dev); if (dev->parent) pm_runtime_put(dev->parent); pm_runtime_put_suppliers(dev); Now pm_runtime_put_suppliers() will put the supplier i.e. rpm_active 2 -> 1, but consumer can still be active. return ret; } Fix by checking the runtime status. For any status other than RPM_SUSPENDED, rpm_active can be considered to be "owned" by rpm_[get/put]_suppliers() and pm_runtime_put_suppliers() need do nothing. Reported-by: Asutosh Das Fixes: 4c06c4e6cf63 ("driver core: Fix possible supplier PM-usage counter imbalance") Signed-off-by: Adrian Hunter --- drivers/base/power/runtime.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c index 4fde37713c58..fe1dad68aee4 100644 --- a/drivers/base/power/runtime.c +++ b/drivers/base/power/runtime.c @@ -1704,6 +1704,8 @@ void pm_runtime_get_suppliers(struct device *dev) void pm_runtime_put_suppliers(struct device *dev) { struct device_link *link; + unsigned long flags; + bool put; int idx; idx = device_links_read_lock(); @@ -1712,7 +1714,11 @@ void pm_runtime_put_suppliers(struct device *dev) device_links_read_lock_held()) if (link->supplier_preactivated) { link->supplier_preactivated = false; - if (refcount_dec_not_one(&link->rpm_active)) + spin_lock_irqsave(&dev->power.lock, flags); + put = pm_runtime_status_suspended(dev) && + refcount_dec_not_one(&link->rpm_active); + spin_unlock_irqrestore(&dev->power.lock, flags); + if (put) pm_runtime_put(link->supplier); }