From 07358194badf73e267289b40b761f5dc56928eab Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Mon, 27 Jun 2022 20:42:18 +0200 Subject: [PATCH 1/2] PM: runtime: Redefine pm_runtime_release_supplier() Instead of passing an extra bool argument to pm_runtime_release_supplier(), make its callers take care of triggering a runtime-suspend of the supplier device as needed. No expected functional impact. Suggested-by: Greg Kroah-Hartman Signed-off-by: Rafael J. Wysocki Reviewed-by: Greg Kroah-Hartman Cc: 5.1+ # 5.1+ --- drivers/base/core.c | 3 ++- drivers/base/power/runtime.c | 20 +++++++++----------- include/linux/pm_runtime.h | 5 ++--- 3 files changed, 13 insertions(+), 15 deletions(-) diff --git a/drivers/base/core.c b/drivers/base/core.c index 7cd789c4985d..58aa49527d3a 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -486,7 +486,8 @@ static void device_link_release_fn(struct work_struct *work) /* Ensure that all references to the link object have been dropped. */ device_link_synchronize_removal(); - pm_runtime_release_supplier(link, true); + pm_runtime_release_supplier(link); + pm_request_idle(link->supplier); put_device(link->consumer); put_device(link->supplier); diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c index 676dc72d912d..23cc4c377d77 100644 --- a/drivers/base/power/runtime.c +++ b/drivers/base/power/runtime.c @@ -308,13 +308,10 @@ static int rpm_get_suppliers(struct device *dev) /** * pm_runtime_release_supplier - Drop references to device link's supplier. * @link: Target device link. - * @check_idle: Whether or not to check if the supplier device is idle. * - * Drop all runtime PM references associated with @link to its supplier device - * and if @check_idle is set, check if that device is idle (and so it can be - * suspended). + * Drop all runtime PM references associated with @link to its supplier device. */ -void pm_runtime_release_supplier(struct device_link *link, bool check_idle) +void pm_runtime_release_supplier(struct device_link *link) { struct device *supplier = link->supplier; @@ -327,9 +324,6 @@ void pm_runtime_release_supplier(struct device_link *link, bool check_idle) while (refcount_dec_not_one(&link->rpm_active) && atomic_read(&supplier->power.usage_count) > 0) pm_runtime_put_noidle(supplier); - - if (check_idle) - pm_request_idle(supplier); } static void __rpm_put_suppliers(struct device *dev, bool try_to_suspend) @@ -337,8 +331,11 @@ static void __rpm_put_suppliers(struct device *dev, bool try_to_suspend) struct device_link *link; list_for_each_entry_rcu(link, &dev->links.suppliers, c_node, - device_links_read_lock_held()) - pm_runtime_release_supplier(link, try_to_suspend); + device_links_read_lock_held()) { + pm_runtime_release_supplier(link); + if (try_to_suspend) + pm_request_idle(link->supplier); + } } static void rpm_put_suppliers(struct device *dev) @@ -1838,7 +1835,8 @@ void pm_runtime_drop_link(struct device_link *link) return; pm_runtime_drop_link_count(link->consumer); - pm_runtime_release_supplier(link, true); + pm_runtime_release_supplier(link); + pm_request_idle(link->supplier); } static bool pm_runtime_need_not_resume(struct device *dev) diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h index 9e4d056967c6..0a41b2dcccad 100644 --- a/include/linux/pm_runtime.h +++ b/include/linux/pm_runtime.h @@ -88,7 +88,7 @@ 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_link *link); -extern void pm_runtime_release_supplier(struct device_link *link, bool check_idle); +extern void pm_runtime_release_supplier(struct device_link *link); extern int devm_pm_runtime_enable(struct device *dev); @@ -314,8 +314,7 @@ 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_link *link) {} -static inline void pm_runtime_release_supplier(struct device_link *link, - bool check_idle) {} +static inline void pm_runtime_release_supplier(struct device_link *link) {} #endif /* !CONFIG_PM */ From 887371066039011144b4a94af97d9328df6869a2 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Thu, 30 Jun 2022 21:16:41 +0200 Subject: [PATCH 2/2] PM: runtime: Fix supplier device management during consumer probe Because pm_runtime_get_suppliers() bumps up the rpm_active counter of each device link to a supplier of the given device in addition to bumping up the supplier's PM-runtime usage counter, a runtime suspend of the consumer device may case the latter to go down to 0 when pm_runtime_put_suppliers() is running on a remote CPU. If that happens after pm_runtime_put_suppliers() has released power.lock for the consumer device, and a runtime resume of that device takes place immediately after it, before pm_runtime_put() is called for the supplier, that pm_runtime_put() call may cause the supplier to be suspended even though the consumer is active. To prevent that from happening, modify pm_runtime_get_suppliers() to call pm_runtime_get_sync() for the given device's suppliers without touching the rpm_active counters of the involved device links Accordingly, modify pm_runtime_put_suppliers() to call pm_runtime_put() for the given device's suppliers without looking at the rpm_active counters of the device links at hand. [This is analogous to what happened before commit 4c06c4e6cf63 ("driver core: Fix possible supplier PM-usage counter imbalance").] Since pm_runtime_get_suppliers() sets supplier_preactivated for each device link where the supplier's PM-runtime usage counter has been incremented and pm_runtime_put_suppliers() calls pm_runtime_put() for the suppliers whose device links have supplier_preactivated set, the PM-runtime usage counter is balanced for each supplier and this is independent of the runtime suspend and resume of the consumer device. However, in case a device link with DL_FLAG_PM_RUNTIME set is dropped during the consumer device probe, so pm_runtime_get_suppliers() bumps up the supplier's PM-runtime usage counter, but it cannot be dropped by pm_runtime_put_suppliers(), make device_link_release_fn() take care of that. Fixes: 4c06c4e6cf63 ("driver core: Fix possible supplier PM-usage counter imbalance") Reported-by: Peter Wang Signed-off-by: Rafael J. Wysocki Reviewed-by: Greg Kroah-Hartman Reviewed-by: Peter Wang Cc: 5.1+ # 5.1+ --- drivers/base/core.c | 10 ++++++++++ drivers/base/power/runtime.c | 14 +------------- 2 files changed, 11 insertions(+), 13 deletions(-) diff --git a/drivers/base/core.c b/drivers/base/core.c index 58aa49527d3a..460d6f163e41 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -487,6 +487,16 @@ static void device_link_release_fn(struct work_struct *work) device_link_synchronize_removal(); pm_runtime_release_supplier(link); + /* + * If supplier_preactivated is set, the link has been dropped between + * the pm_runtime_get_suppliers() and pm_runtime_put_suppliers() calls + * in __driver_probe_device(). In that case, drop the supplier's + * PM-runtime usage counter to remove the reference taken by + * pm_runtime_get_suppliers(). + */ + if (link->supplier_preactivated) + pm_runtime_put_noidle(link->supplier); + pm_request_idle(link->supplier); put_device(link->consumer); diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c index 23cc4c377d77..949907e2e242 100644 --- a/drivers/base/power/runtime.c +++ b/drivers/base/power/runtime.c @@ -1768,7 +1768,6 @@ void pm_runtime_get_suppliers(struct device *dev) if (link->flags & DL_FLAG_PM_RUNTIME) { link->supplier_preactivated = true; pm_runtime_get_sync(link->supplier); - refcount_inc(&link->rpm_active); } device_links_read_unlock(idx); @@ -1788,19 +1787,8 @@ void pm_runtime_put_suppliers(struct device *dev) list_for_each_entry_rcu(link, &dev->links.suppliers, c_node, device_links_read_lock_held()) if (link->supplier_preactivated) { - bool put; - link->supplier_preactivated = false; - - spin_lock_irq(&dev->power.lock); - - put = pm_runtime_status_suspended(dev) && - refcount_dec_not_one(&link->rpm_active); - - spin_unlock_irq(&dev->power.lock); - - if (put) - pm_runtime_put(link->supplier); + pm_runtime_put(link->supplier); } device_links_read_unlock(idx);