From baa8809f60971d10220dfe79248f54b2b265f003 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Sun, 30 Oct 2016 17:32:43 +0100 Subject: PM / runtime: Optimize the use of device links 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 Signed-off-by: Greg Kroah-Hartman --- drivers/base/core.c | 20 +++++++++++++------- drivers/base/power/runtime.c | 23 ++++++++++++++++++++--- include/linux/pm.h | 1 + include/linux/pm_runtime.h | 4 ++++ 4 files changed, 38 insertions(+), 10 deletions(-) diff --git a/drivers/base/core.c b/drivers/base/core.c index 876c62b..d0c9df5 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -205,14 +205,17 @@ struct device_link *device_link_add(struct device *consumer, if (!link) goto out; - if ((flags & DL_FLAG_PM_RUNTIME) && (flags & DL_FLAG_RPM_ACTIVE)) { - if (pm_runtime_get_sync(supplier) < 0) { - pm_runtime_put_noidle(supplier); - kfree(link); - link = NULL; - goto out; + if (flags & DL_FLAG_PM_RUNTIME) { + if (flags & DL_FLAG_RPM_ACTIVE) { + if (pm_runtime_get_sync(supplier) < 0) { + pm_runtime_put_noidle(supplier); + kfree(link); + link = NULL; + goto out; + } + link->rpm_active = true; } - link->rpm_active = true; + pm_runtime_new_link(consumer); } get_device(supplier); link->supplier = supplier; @@ -296,6 +299,9 @@ static void __device_link_del(struct device_link *link) dev_info(link->consumer, "Dropping the link to %s\n", dev_name(link->supplier)); + if (link->flags & DL_FLAG_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); diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c index 462f90e..ba7b4a8 100644 --- a/drivers/base/power/runtime.c +++ b/drivers/base/power/runtime.c @@ -305,6 +305,7 @@ static int __rpm_callback(int (*cb)(struct device *), struct device *dev) __releases(&dev->power.lock) __acquires(&dev->power.lock) { int retval, idx; + bool use_links = dev->power.links_count > 0; if (dev->power.irq_safe) { spin_unlock(&dev->power.lock); @@ -318,7 +319,7 @@ static int __rpm_callback(int (*cb)(struct device *), struct device *dev) * 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(); retval = rpm_get_suppliers(dev); @@ -341,8 +342,9 @@ static int __rpm_callback(int (*cb)(struct device *), struct device *dev) * * 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: @@ -1593,6 +1595,21 @@ void pm_runtime_put_suppliers(struct device *dev) 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. diff --git a/include/linux/pm.h b/include/linux/pm.h index 721a702..ccfe00e 100644 --- a/include/linux/pm.h +++ b/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; diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h index c2ee871..7381487 100644 --- a/include/linux/pm_runtime.h +++ b/include/linux/pm_runtime.h @@ -58,6 +58,8 @@ 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_get_suppliers(struct device *dev); extern void pm_runtime_put_suppliers(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) { @@ -192,6 +194,8 @@ static inline void pm_runtime_set_memalloc_noio(struct device *dev, static inline void pm_runtime_clean_up_links(struct device *dev) {} static inline void pm_runtime_get_suppliers(struct device *dev) {} static inline void pm_runtime_put_suppliers(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 */ -- cgit v1.1