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=-17.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 565D6C4361A for ; Fri, 4 Dec 2020 23:22:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 303D022519 for ; Fri, 4 Dec 2020 23:22:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727368AbgLDXWI (ORCPT ); Fri, 4 Dec 2020 18:22:08 -0500 Received: from mail.kernel.org ([198.145.29.99]:35786 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726508AbgLDXWI (ORCPT ); Fri, 4 Dec 2020 18:22:08 -0500 Date: Fri, 4 Dec 2020 17:21:25 -0600 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1607124087; bh=jcN9PbMgOLCkW/eP5nH6XSM0/5/dbV78dPtpbOxyH3w=; h=From:To:Cc:Subject:In-Reply-To:From; b=QqgauAw1WS/afGO36xcC6AzO0lwg2sUSG5XaJj47SNxVwB45+PaMKQyXPTE1uxA2D 2ADrk6Hd+aNpzENCvjKpuKfjWvTDaIcuyXqRKMZiZVn55JjPa6jIFG1rh2HP1R9aRs kjyT1dcfh6WUCZkjSBb7yvMA6hLuvk+YBxh8tFx9P4PwZ+d4ww5QtWSXClEQLmFb7c HVjZh/rfpG6uKfoYj8jn2+8Ah4HHR5iBBMP/j6vTUG+UsPcYK147BJBxb9g9LLJzSF RfkSYJkNRPiPLQd1fztTn/GP+y1oDuj4qOAApBEQbQaXopbp5PQpBfRpzu7Ry/8BtQ XC7S7TNYdcRUw== From: Bjorn Helgaas To: "Rafael J. Wysocki" Cc: Linux ACPI , LKML , Linux PM , Linux PCI , Mika Westerberg , "Rafael J. Wysocki" , Kai-Heng Feng Subject: Re: [PATCH v1 1/2] PM: ACPI: PCI: Drop acpi_pm_set_bridge_wakeup() Message-ID: <20201204232125.GA1981160@bjorn-Precision-5520> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2261308.G18gbxz5ee@kreacher> Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Tue, Nov 24, 2020 at 08:44:00PM +0100, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki > > The idea behind acpi_pm_set_bridge_wakeup() was to allow bridges to > be reference counted for wakeup enabling, because they may be enabled > to signal wakeup on behalf of their subordinate devices and that > may happen for multiple times in a row, whereas for the other devices > it only makes sense to enable wakeup signaling once. > > However, this becomes problematic if the bridge itself is suspended, > because it is treated as a "regular" device in that case and the > reference counting doesn't work. > > For instance, suppose that there are two devices below a bridge and > they both can signal wakeup. Every time one of them is suspended, > wakeup signaling is enabled for the bridge, so when they both have > been suspended, the bridge's wakeup reference counter value is 2. > > Say that the bridge is suspended subsequently and acpi_pci_wakeup() > is called for it. Because the bridge can signal wakeup, that > function will invoke acpi_pm_set_device_wakeup() to configure it > and __acpi_pm_set_device_wakeup() will be called with the last > argument equal to 1. This causes __acpi_device_wakeup_enable() > invoked by it to omit the reference counting, because the reference > counter of the target device (the bridge) is 2 at that time. > > Now say that the bridge resumes and one of the device below it > resumes too, so the bridge's reference counter becomes 0 and > wakeup signaling is disabled for it, but there is still the other > suspended device which may need the bridge to signal wakeup on its > behalf and that is not going to work. > > To address this scenario, use wakeup enable reference counting for > all devices, not just for bridges, so drop the last argument from > __acpi_device_wakeup_enable() and __acpi_pm_set_device_wakeup(), > which causes acpi_pm_set_device_wakeup() and > acpi_pm_set_bridge_wakeup() to become identical, so drop the latter > and use the former instead of it everywhere. > > Signed-off-by: Rafael J. Wysocki Acked-by: Bjorn Helgaas > --- > drivers/acpi/device_pm.c | 41 ++++++++++++----------------------------- > drivers/pci/pci-acpi.c | 4 ++-- > include/acpi/acpi_bus.h | 5 ----- > 3 files changed, 14 insertions(+), 36 deletions(-) > > Index: linux-pm/include/acpi/acpi_bus.h > =================================================================== > --- linux-pm.orig/include/acpi/acpi_bus.h > +++ linux-pm/include/acpi/acpi_bus.h > @@ -620,7 +620,6 @@ acpi_status acpi_remove_pm_notifier(stru > bool acpi_pm_device_can_wakeup(struct device *dev); > int acpi_pm_device_sleep_state(struct device *, int *, int); > int acpi_pm_set_device_wakeup(struct device *dev, bool enable); > -int acpi_pm_set_bridge_wakeup(struct device *dev, bool enable); > #else > static inline void acpi_pm_wakeup_event(struct device *dev) > { > @@ -651,10 +650,6 @@ static inline int acpi_pm_set_device_wak > { > return -ENODEV; > } > -static inline int acpi_pm_set_bridge_wakeup(struct device *dev, bool enable) > -{ > - return -ENODEV; > -} > #endif > > #ifdef CONFIG_ACPI_SYSTEM_POWER_STATES_SUPPORT > Index: linux-pm/drivers/acpi/device_pm.c > =================================================================== > --- linux-pm.orig/drivers/acpi/device_pm.c > +++ linux-pm/drivers/acpi/device_pm.c > @@ -749,7 +749,7 @@ static void acpi_pm_notify_work_func(str > static DEFINE_MUTEX(acpi_wakeup_lock); > > static int __acpi_device_wakeup_enable(struct acpi_device *adev, > - u32 target_state, int max_count) > + u32 target_state) > { > struct acpi_device_wakeup *wakeup = &adev->wakeup; > acpi_status status; > @@ -757,9 +757,10 @@ static int __acpi_device_wakeup_enable(s > > mutex_lock(&acpi_wakeup_lock); > > - if (wakeup->enable_count >= max_count) > + if (wakeup->enable_count >= INT_MAX) { > + acpi_handle_info(adev->handle, "Wakeup enable count out of bounds!\n"); > goto out; > - > + } > if (wakeup->enable_count > 0) > goto inc; > > @@ -799,7 +800,7 @@ out: > */ > static int acpi_device_wakeup_enable(struct acpi_device *adev, u32 target_state) > { > - return __acpi_device_wakeup_enable(adev, target_state, 1); > + return __acpi_device_wakeup_enable(adev, target_state); > } > > /** > @@ -829,8 +830,12 @@ out: > mutex_unlock(&acpi_wakeup_lock); > } > > -static int __acpi_pm_set_device_wakeup(struct device *dev, bool enable, > - int max_count) > +/** > + * acpi_pm_set_device_wakeup - Enable/disable remote wakeup for given device. > + * @dev: Device to enable/disable to generate wakeup events. > + * @enable: Whether to enable or disable the wakeup functionality. > + */ > +int acpi_pm_set_device_wakeup(struct device *dev, bool enable) > { > struct acpi_device *adev; > int error; > @@ -850,37 +855,15 @@ static int __acpi_pm_set_device_wakeup(s > return 0; > } > > - error = __acpi_device_wakeup_enable(adev, acpi_target_system_state(), > - max_count); > + error = __acpi_device_wakeup_enable(adev, acpi_target_system_state()); > if (!error) > dev_dbg(dev, "Wakeup enabled by ACPI\n"); > > return error; > } > - > -/** > - * acpi_pm_set_device_wakeup - Enable/disable remote wakeup for given device. > - * @dev: Device to enable/disable to generate wakeup events. > - * @enable: Whether to enable or disable the wakeup functionality. > - */ > -int acpi_pm_set_device_wakeup(struct device *dev, bool enable) > -{ > - return __acpi_pm_set_device_wakeup(dev, enable, 1); > -} > EXPORT_SYMBOL_GPL(acpi_pm_set_device_wakeup); > > /** > - * acpi_pm_set_bridge_wakeup - Enable/disable remote wakeup for given bridge. > - * @dev: Bridge device to enable/disable to generate wakeup events. > - * @enable: Whether to enable or disable the wakeup functionality. > - */ > -int acpi_pm_set_bridge_wakeup(struct device *dev, bool enable) > -{ > - return __acpi_pm_set_device_wakeup(dev, enable, INT_MAX); > -} > -EXPORT_SYMBOL_GPL(acpi_pm_set_bridge_wakeup); > - > -/** > * acpi_dev_pm_low_power - Put ACPI device into a low-power state. > * @dev: Device to put into a low-power state. > * @adev: ACPI device node corresponding to @dev. > Index: linux-pm/drivers/pci/pci-acpi.c > =================================================================== > --- linux-pm.orig/drivers/pci/pci-acpi.c > +++ linux-pm/drivers/pci/pci-acpi.c > @@ -1060,7 +1060,7 @@ static int acpi_pci_propagate_wakeup(str > { > while (bus->parent) { > if (acpi_pm_device_can_wakeup(&bus->self->dev)) > - return acpi_pm_set_bridge_wakeup(&bus->self->dev, enable); > + return acpi_pm_set_device_wakeup(&bus->self->dev, enable); > > bus = bus->parent; > } > @@ -1068,7 +1068,7 @@ static int acpi_pci_propagate_wakeup(str > /* We have reached the root bus. */ > if (bus->bridge) { > if (acpi_pm_device_can_wakeup(bus->bridge)) > - return acpi_pm_set_bridge_wakeup(bus->bridge, enable); > + return acpi_pm_set_device_wakeup(bus->bridge, enable); > } > return 0; > } > > >