From 3a4a0042228a854d9b1073050620820b4a977e6e Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Wed, 12 Feb 2020 00:02:30 +0100 Subject: [PATCH] PM: QoS: Drop PM_QOS_CPU_DMA_LATENCY notifier chain Notice that pm_qos_remove_notifier() is not used at all and the only caller of pm_qos_add_notifier() is the cpuidle core, which only needs the PM_QOS_CPU_DMA_LATENCY notifier to invoke wake_up_all_idle_cpus() upon changes of the PM_QOS_CPU_DMA_LATENCY target value. First, to ensure that wake_up_all_idle_cpus() will be called whenever the PM_QOS_CPU_DMA_LATENCY target value changes, modify the pm_qos_add/update/remove_request() family of functions to check if the effective constraint for the PM_QOS_CPU_DMA_LATENCY has changed and call wake_up_all_idle_cpus() directly in that case. Next, drop the PM_QOS_CPU_DMA_LATENCY notifier from cpuidle as it is not necessary any more. Finally, drop both pm_qos_add_notifier() and pm_qos_remove_notifier(), as they have no callers now, along with cpu_dma_lat_notifier which is only used by them. Signed-off-by: Rafael J. Wysocki Reviewed-by: Ulf Hansson Reviewed-by: Amit Kucheria Tested-by: Amit Kucheria --- drivers/cpuidle/cpuidle.c | 40 +-------------------------------- include/linux/pm_qos.h | 2 -- kernel/power/qos.c | 47 +++++++++------------------------------ 3 files changed, 12 insertions(+), 77 deletions(-) diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index de81298051b3..c149d9e20dfd 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -736,53 +736,15 @@ int cpuidle_register(struct cpuidle_driver *drv, } EXPORT_SYMBOL_GPL(cpuidle_register); -#ifdef CONFIG_SMP - -/* - * This function gets called when a part of the kernel has a new latency - * requirement. This means we need to get all processors out of their C-state, - * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that - * wakes them all right up. - */ -static int cpuidle_latency_notify(struct notifier_block *b, - unsigned long l, void *v) -{ - wake_up_all_idle_cpus(); - return NOTIFY_OK; -} - -static struct notifier_block cpuidle_latency_notifier = { - .notifier_call = cpuidle_latency_notify, -}; - -static inline void latency_notifier_init(struct notifier_block *n) -{ - pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n); -} - -#else /* CONFIG_SMP */ - -#define latency_notifier_init(x) do { } while (0) - -#endif /* CONFIG_SMP */ - /** * cpuidle_init - core initializer */ static int __init cpuidle_init(void) { - int ret; - if (cpuidle_disabled()) return -ENODEV; - ret = cpuidle_add_interface(cpu_subsys.dev_root); - if (ret) - return ret; - - latency_notifier_init(&cpuidle_latency_notifier); - - return 0; + return cpuidle_add_interface(cpu_subsys.dev_root); } module_param(off, int, 0444); diff --git a/include/linux/pm_qos.h b/include/linux/pm_qos.h index bef110aa80cc..cb57e5918a25 100644 --- a/include/linux/pm_qos.h +++ b/include/linux/pm_qos.h @@ -149,8 +149,6 @@ void pm_qos_update_request(struct pm_qos_request *req, void pm_qos_remove_request(struct pm_qos_request *req); int pm_qos_request(int pm_qos_class); -int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier); -int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier); int pm_qos_request_active(struct pm_qos_request *req); s32 pm_qos_read_value(struct pm_qos_constraints *c); diff --git a/kernel/power/qos.c b/kernel/power/qos.c index 952c5f55e23c..201b43bc6457 100644 --- a/kernel/power/qos.c +++ b/kernel/power/qos.c @@ -56,14 +56,12 @@ */ static DEFINE_SPINLOCK(pm_qos_lock); -static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier); static struct pm_qos_constraints cpu_dma_constraints = { .list = PLIST_HEAD_INIT(cpu_dma_constraints.list), .target_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE, .default_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE, .no_constraint_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE, .type = PM_QOS_MIN, - .notifiers = &cpu_dma_lat_notifier, }; /** @@ -247,6 +245,14 @@ int pm_qos_request_active(struct pm_qos_request *req) } EXPORT_SYMBOL_GPL(pm_qos_request_active); +static void cpu_latency_qos_update(struct pm_qos_request *req, + enum pm_qos_req_action action, s32 value) +{ + int ret = pm_qos_update_target(req->qos, &req->node, action, value); + if (ret > 0) + wake_up_all_idle_cpus(); +} + /** * pm_qos_add_request - inserts new qos request into the list * @req: pointer to a preallocated handle @@ -273,7 +279,7 @@ void pm_qos_add_request(struct pm_qos_request *req, trace_pm_qos_add_request(PM_QOS_CPU_DMA_LATENCY, value); req->qos = &cpu_dma_constraints; - pm_qos_update_target(req->qos, &req->node, PM_QOS_ADD_REQ, value); + cpu_latency_qos_update(req, PM_QOS_ADD_REQ, value); } EXPORT_SYMBOL_GPL(pm_qos_add_request); @@ -302,7 +308,7 @@ void pm_qos_update_request(struct pm_qos_request *req, s32 new_value) if (new_value == req->node.prio) return; - pm_qos_update_target(req->qos, &req->node, PM_QOS_UPDATE_REQ, new_value); + cpu_latency_qos_update(req, PM_QOS_UPDATE_REQ, new_value); } EXPORT_SYMBOL_GPL(pm_qos_update_request); @@ -327,42 +333,11 @@ void pm_qos_remove_request(struct pm_qos_request *req) trace_pm_qos_remove_request(PM_QOS_CPU_DMA_LATENCY, PM_QOS_DEFAULT_VALUE); - pm_qos_update_target(req->qos, &req->node, PM_QOS_REMOVE_REQ, - PM_QOS_DEFAULT_VALUE); + cpu_latency_qos_update(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE); memset(req, 0, sizeof(*req)); } EXPORT_SYMBOL_GPL(pm_qos_remove_request); -/** - * pm_qos_add_notifier - sets notification entry for changes to target value - * @pm_qos_class: Ignored. - * @notifier: notifier block managed by caller. - * - * will register the notifier into a notification chain that gets called - * upon changes to the PM_QOS_CPU_DMA_LATENCY target value. - */ -int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier) -{ - return blocking_notifier_chain_register(cpu_dma_constraints.notifiers, - notifier); -} -EXPORT_SYMBOL_GPL(pm_qos_add_notifier); - -/** - * pm_qos_remove_notifier - deletes notification entry from chain. - * @pm_qos_class: Ignored. - * @notifier: notifier block to be removed. - * - * will remove the notifier from the notification chain that gets called - * upon changes to the PM_QOS_CPU_DMA_LATENCY target value. - */ -int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier) -{ - return blocking_notifier_chain_unregister(cpu_dma_constraints.notifiers, - notifier); -} -EXPORT_SYMBOL_GPL(pm_qos_remove_notifier); - /* User space interface to global PM QoS via misc device. */ static int pm_qos_power_open(struct inode *inode, struct file *filp)