From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758576AbcIHVZx (ORCPT ); Thu, 8 Sep 2016 17:25:53 -0400 Received: from cloudserver094114.home.net.pl ([79.96.170.134]:42613 "HELO cloudserver094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751143AbcIHVZu (ORCPT ); Thu, 8 Sep 2016 17:25:50 -0400 From: "Rafael J. Wysocki" To: Linux PM list Cc: Greg Kroah-Hartman , Alan Stern , Linux Kernel Mailing List , Tomeu Vizoso , Mark Brown , Marek Szyprowski , Lukas Wunner , Kevin Hilman , Ulf Hansson , "Luis R. Rodriguez" Subject: [RFC/RFT][PATCH v2 7/7] PM / runtime: Optimize the use of device links Date: Thu, 08 Sep 2016 23:31:01 +0200 Message-ID: <8730255.jrQATcHMJn@vostro.rjw.lan> User-Agent: KMail/4.11.5 (Linux/4.8.0-rc2+; KDE/4.11.5; x86_64; ; ) In-Reply-To: <27296716.H9VWo8ShOm@vostro.rjw.lan> References: <27296716.H9VWo8ShOm@vostro.rjw.lan> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Rafael J. Wysocki If the device has no links to suppliers that should be used for runtime PM (links with DEVICE_LINK_PM_RUNTIME set), there is no reason to walk the list of suppliers for that device during runtime suspend and resume. Add a simple mechanism to detect that case and possibly avoid the extra unnecessary overhead. Signed-off-by: Rafael J. Wysocki --- drivers/base/core.c | 6 ++++++ drivers/base/power/runtime.c | 23 ++++++++++++++++++++--- include/linux/pm.h | 1 + include/linux/pm_runtime.h | 4 ++++ 4 files changed, 31 insertions(+), 3 deletions(-) Index: linux-pm/drivers/base/core.c =================================================================== --- linux-pm.orig/drivers/base/core.c +++ linux-pm/drivers/base/core.c @@ -151,6 +151,9 @@ struct device_link *device_link_add(stru link->consumer = consumer; INIT_LIST_HEAD(&link->c_node); spin_lock_init(&link->lock); + if (flags & DEVICE_LINK_PM_RUNTIME) + pm_runtime_new_link(consumer); + link->flags = flags; link->status = status; @@ -191,6 +194,9 @@ static void __device_link_del(struct dev dev_info(link->consumer, "Dropping the link to %s\n", dev_name(link->supplier)); + if (link->flags & DEVICE_LINK_PM_RUNTIME) + pm_runtime_drop_link(link->consumer); + list_del_rcu(&link->s_node); list_del_rcu(&link->c_node); call_srcu(&device_links_srcu, &link->rcu_head, __device_link_free_srcu); Index: linux-pm/drivers/base/power/runtime.c =================================================================== --- linux-pm.orig/drivers/base/power/runtime.c +++ linux-pm/drivers/base/power/runtime.c @@ -270,6 +270,7 @@ static int __rpm_callback(int (*cb)(stru { struct device_link *link; int retval, idx; + bool use_links = dev->power.links_count > 0; if (dev->power.irq_safe) { spin_unlock(&dev->power.lock); @@ -283,7 +284,7 @@ static int __rpm_callback(int (*cb)(stru * routine returns, so it is safe to read the status outside of * the lock. */ - if (dev->power.runtime_status == RPM_RESUMING) { + if (use_links && dev->power.runtime_status == RPM_RESUMING) { idx = device_links_read_lock(); list_for_each_entry_rcu(link, &dev->links_to_suppliers, c_node) @@ -314,8 +315,9 @@ static int __rpm_callback(int (*cb)(stru * * Do that if resume fails too. */ - if ((dev->power.runtime_status == RPM_SUSPENDING && !retval) - || (dev->power.runtime_status == RPM_RESUMING && retval)) { + if (use_links + && ((dev->power.runtime_status == RPM_SUSPENDING && !retval) + || (dev->power.runtime_status == RPM_RESUMING && retval))) { idx = device_links_read_lock(); fail: @@ -1546,6 +1548,21 @@ void pm_runtime_clean_up_links(struct de device_links_read_unlock(idx); } +void pm_runtime_new_link(struct device *dev) +{ + spin_lock_irq(&dev->power.lock); + dev->power.links_count++; + spin_unlock_irq(&dev->power.lock); +} + +void pm_runtime_drop_link(struct device *dev) +{ + spin_lock_irq(&dev->power.lock); + WARN_ON(dev->power.links_count == 0); + dev->power.links_count--; + spin_unlock_irq(&dev->power.lock); +} + /** * pm_runtime_force_suspend - Force a device into suspend state if needed. * @dev: Device to suspend. Index: linux-pm/include/linux/pm.h =================================================================== --- linux-pm.orig/include/linux/pm.h +++ linux-pm/include/linux/pm.h @@ -597,6 +597,7 @@ struct dev_pm_info { unsigned int use_autosuspend:1; unsigned int timer_autosuspends:1; unsigned int memalloc_noio:1; + unsigned int links_count; enum rpm_request request; enum rpm_status runtime_status; int runtime_error; Index: linux-pm/include/linux/pm_runtime.h =================================================================== --- linux-pm.orig/include/linux/pm_runtime.h +++ linux-pm/include/linux/pm_runtime.h @@ -62,6 +62,8 @@ extern void pm_runtime_update_max_time_s s64 delta_ns); extern void pm_runtime_set_memalloc_noio(struct device *dev, bool enable); extern void pm_runtime_clean_up_links(struct device *dev); +extern void pm_runtime_new_link(struct device *dev); +extern void pm_runtime_drop_link(struct device *dev); static inline void pm_suspend_ignore_children(struct device *dev, bool enable) { @@ -194,6 +196,8 @@ static inline unsigned long pm_runtime_a static inline void pm_runtime_set_memalloc_noio(struct device *dev, bool enable){} static inline void pm_runtime_clean_up_links(struct device *dev) {} +static inline void pm_runtime_new_link(struct device *dev) {} +static inline void pm_runtime_drop_link(struct device *dev) {} #endif /* !CONFIG_PM */