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PM QoS: Use spinlock in the per-device PM QoS constraints code

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The per-device PM QoS locking requires a spinlock to be used. The reasons
are:
 - an alignement with the PM QoS core code, which is used by the per-device
   PM QoS code for the constraints lists management. The PM QoS core code
   uses spinlocks to protect the constraints lists,
 - some drivers need to use the per-device PM QoS functionality from
   interrupt context or spinlock protected context.
   An example of such a driver is the OMAP HSI (high-speed synchronous serial
   interface) driver which needs to control the IP block idle state
   depending on the FIFO empty state, from interrupt context.

Reported-by: Djamil Elaidi <d-elaidi@ti.com>
Signed-off-by: Jean Pihet <j-pihet@ti.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
This commit is contained in:
Jean Pihet 2012-09-19 14:17:20 +02:00 committed by Rafael J. Wysocki
parent c6a57bfffe
commit fc2fb3a075
1 changed files with 41 additions and 26 deletions
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67
drivers/base/power/qos.c
View File

@ -24,26 +24,32 @@
* . a system-wide notification callback using the dev_pm_qos_*_global_notifier * . a system-wide notification callback using the dev_pm_qos_*_global_notifier
* API. The notification chain data is stored in a static variable. * API. The notification chain data is stored in a static variable.
* *
* Note about the per-device constraint data struct allocation: * Notes about the per-device constraint data struct allocation:
* . The per-device constraints data struct ptr is tored into the device * . The per-device constraints data struct ptr is stored into the device
* dev_pm_info. * dev_pm_info.
* . To minimize the data usage by the per-device constraints, the data struct * . To minimize the data usage by the per-device constraints, the data struct
* is only allocated at the first call to dev_pm_qos_add_request. * is only allocated at the first call to dev_pm_qos_add_request.
* . The data is later free'd when the device is removed from the system. * . The data is later free'd when the device is removed from the system.
* . A global mutex protects the constraints users from the data being *
* allocated and free'd. * Notes about locking:
* . The dev->power.lock lock protects the constraints list
* (dev->power.constraints) allocation and free, as triggered by the
* driver core code at device insertion and removal,
* . A global lock dev_pm_qos_lock protects the constraints list entries
* from any modification and the notifiers registration and unregistration.
* . For both locks a spinlock is needed since this code can be called from
* interrupt context or spinlock protected context.
*/ */
#include <linux/pm_qos.h> #include <linux/pm_qos.h>
#include <linux/spinlock.h> #include <linux/spinlock.h>
#include <linux/slab.h> #include <linux/slab.h>
#include <linux/device.h> #include <linux/device.h>
#include <linux/mutex.h>
#include <linux/export.h> #include <linux/export.h>
#include "power.h" #include "power.h"
static DEFINE_MUTEX(dev_pm_qos_mtx); static DEFINE_SPINLOCK(dev_pm_qos_lock);
static BLOCKING_NOTIFIER_HEAD(dev_pm_notifiers); static BLOCKING_NOTIFIER_HEAD(dev_pm_notifiers);
@ -110,18 +116,19 @@ static int apply_constraint(struct dev_pm_qos_request *req,
* @dev: device to allocate data for * @dev: device to allocate data for
* *
* Called at the first call to add_request, for constraint data allocation * Called at the first call to add_request, for constraint data allocation
* Must be called with the dev_pm_qos_mtx mutex held * Must be called with the dev_pm_qos_lock lock held
*/ */
static int dev_pm_qos_constraints_allocate(struct device *dev) static int dev_pm_qos_constraints_allocate(struct device *dev)
{ {
struct pm_qos_constraints *c; struct pm_qos_constraints *c;
struct blocking_notifier_head *n; struct blocking_notifier_head *n;
unsigned long flags;
c = kzalloc(sizeof(*c), GFP_KERNEL); c = kzalloc(sizeof(*c), GFP_ATOMIC);
if (!c) if (!c)
return -ENOMEM; return -ENOMEM;
n = kzalloc(sizeof(*n), GFP_KERNEL); n = kzalloc(sizeof(*n), GFP_ATOMIC);
if (!n) { if (!n) {
kfree(c); kfree(c);
return -ENOMEM; return -ENOMEM;
@ -134,9 +141,9 @@ static int dev_pm_qos_constraints_allocate(struct device *dev)
c->type = PM_QOS_MIN; c->type = PM_QOS_MIN;
c->notifiers = n; c->notifiers = n;
spin_lock_irq(&dev->power.lock); spin_lock_irqsave(&dev->power.lock, flags);
dev->power.constraints = c; dev->power.constraints = c;
spin_unlock_irq(&dev->power.lock); spin_unlock_irqrestore(&dev->power.lock, flags);
return 0; return 0;
} }
@ -150,10 +157,12 @@ static int dev_pm_qos_constraints_allocate(struct device *dev)
*/ */
void dev_pm_qos_constraints_init(struct device *dev) void dev_pm_qos_constraints_init(struct device *dev)
{ {
mutex_lock(&dev_pm_qos_mtx); unsigned long flags;
spin_lock_irqsave(&dev_pm_qos_lock, flags);
dev->power.constraints = NULL; dev->power.constraints = NULL;
dev->power.power_state = PMSG_ON; dev->power.power_state = PMSG_ON;
mutex_unlock(&dev_pm_qos_mtx); spin_unlock_irqrestore(&dev_pm_qos_lock, flags);
} }
/** /**
@ -166,6 +175,7 @@ void dev_pm_qos_constraints_destroy(struct device *dev)
{ {
struct dev_pm_qos_request *req, *tmp; struct dev_pm_qos_request *req, *tmp;
struct pm_qos_constraints *c; struct pm_qos_constraints *c;
unsigned long flags;
/* /*
* If the device's PM QoS resume latency limit has been exposed to user * If the device's PM QoS resume latency limit has been exposed to user
@ -173,7 +183,7 @@ void dev_pm_qos_constraints_destroy(struct device *dev)
*/ */
dev_pm_qos_hide_latency_limit(dev); dev_pm_qos_hide_latency_limit(dev);
mutex_lock(&dev_pm_qos_mtx); spin_lock_irqsave(&dev_pm_qos_lock, flags);
dev->power.power_state = PMSG_INVALID; dev->power.power_state = PMSG_INVALID;
c = dev->power.constraints; c = dev->power.constraints;
@ -198,7 +208,7 @@ void dev_pm_qos_constraints_destroy(struct device *dev)
kfree(c); kfree(c);
out: out:
mutex_unlock(&dev_pm_qos_mtx); spin_unlock_irqrestore(&dev_pm_qos_lock, flags);
} }
/** /**
@ -223,6 +233,7 @@ int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req,
s32 value) s32 value)
{ {
int ret = 0; int ret = 0;
unsigned long flags;
if (!dev || !req) /*guard against callers passing in null */ if (!dev || !req) /*guard against callers passing in null */
return -EINVAL; return -EINVAL;
@ -233,7 +244,7 @@ int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req,
req->dev = dev; req->dev = dev;
mutex_lock(&dev_pm_qos_mtx); spin_lock_irqsave(&dev_pm_qos_lock, flags);
if (!dev->power.constraints) { if (!dev->power.constraints) {
if (dev->power.power_state.event == PM_EVENT_INVALID) { if (dev->power.power_state.event == PM_EVENT_INVALID) {
@ -255,7 +266,7 @@ int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req,
ret = apply_constraint(req, PM_QOS_ADD_REQ, value); ret = apply_constraint(req, PM_QOS_ADD_REQ, value);
out: out:
mutex_unlock(&dev_pm_qos_mtx); spin_unlock_irqrestore(&dev_pm_qos_lock, flags);
return ret; return ret;
} }
@ -280,6 +291,7 @@ int dev_pm_qos_update_request(struct dev_pm_qos_request *req,
s32 new_value) s32 new_value)
{ {
int ret = 0; int ret = 0;
unsigned long flags;
if (!req) /*guard against callers passing in null */ if (!req) /*guard against callers passing in null */
return -EINVAL; return -EINVAL;
@ -288,7 +300,7 @@ int dev_pm_qos_update_request(struct dev_pm_qos_request *req,
"%s() called for unknown object\n", __func__)) "%s() called for unknown object\n", __func__))
return -EINVAL; return -EINVAL;
mutex_lock(&dev_pm_qos_mtx); spin_lock_irqsave(&dev_pm_qos_lock, flags);
if (req->dev->power.constraints) { if (req->dev->power.constraints) {
if (new_value != req->node.prio) if (new_value != req->node.prio)
@ -299,7 +311,7 @@ int dev_pm_qos_update_request(struct dev_pm_qos_request *req,
ret = -ENODEV; ret = -ENODEV;
} }
mutex_unlock(&dev_pm_qos_mtx); spin_unlock_irqrestore(&dev_pm_qos_lock, flags);
return ret; return ret;
} }
EXPORT_SYMBOL_GPL(dev_pm_qos_update_request); EXPORT_SYMBOL_GPL(dev_pm_qos_update_request);
@ -319,6 +331,7 @@ EXPORT_SYMBOL_GPL(dev_pm_qos_update_request);
int dev_pm_qos_remove_request(struct dev_pm_qos_request *req) int dev_pm_qos_remove_request(struct dev_pm_qos_request *req)
{ {
int ret = 0; int ret = 0;
unsigned long flags;
if (!req) /*guard against callers passing in null */ if (!req) /*guard against callers passing in null */
return -EINVAL; return -EINVAL;
@ -327,7 +340,7 @@ int dev_pm_qos_remove_request(struct dev_pm_qos_request *req)
"%s() called for unknown object\n", __func__)) "%s() called for unknown object\n", __func__))
return -EINVAL; return -EINVAL;
mutex_lock(&dev_pm_qos_mtx); spin_lock_irqsave(&dev_pm_qos_lock, flags);
if (req->dev->power.constraints) { if (req->dev->power.constraints) {
ret = apply_constraint(req, PM_QOS_REMOVE_REQ, ret = apply_constraint(req, PM_QOS_REMOVE_REQ,
@ -338,7 +351,7 @@ int dev_pm_qos_remove_request(struct dev_pm_qos_request *req)
ret = -ENODEV; ret = -ENODEV;
} }
mutex_unlock(&dev_pm_qos_mtx); spin_unlock_irqrestore(&dev_pm_qos_lock, flags);
return ret; return ret;
} }
EXPORT_SYMBOL_GPL(dev_pm_qos_remove_request); EXPORT_SYMBOL_GPL(dev_pm_qos_remove_request);
@ -359,8 +372,9 @@ EXPORT_SYMBOL_GPL(dev_pm_qos_remove_request);
int dev_pm_qos_add_notifier(struct device *dev, struct notifier_block *notifier) int dev_pm_qos_add_notifier(struct device *dev, struct notifier_block *notifier)
{ {
int ret = 0; int ret = 0;
unsigned long flags;
mutex_lock(&dev_pm_qos_mtx); spin_lock_irqsave(&dev_pm_qos_lock, flags);
if (!dev->power.constraints) if (!dev->power.constraints)
ret = dev->power.power_state.event != PM_EVENT_INVALID ? ret = dev->power.power_state.event != PM_EVENT_INVALID ?
@ -370,7 +384,7 @@ int dev_pm_qos_add_notifier(struct device *dev, struct notifier_block *notifier)
ret = blocking_notifier_chain_register( ret = blocking_notifier_chain_register(
dev->power.constraints->notifiers, notifier); dev->power.constraints->notifiers, notifier);
mutex_unlock(&dev_pm_qos_mtx); spin_unlock_irqrestore(&dev_pm_qos_lock, flags);
return ret; return ret;
} }
EXPORT_SYMBOL_GPL(dev_pm_qos_add_notifier); EXPORT_SYMBOL_GPL(dev_pm_qos_add_notifier);
@ -389,8 +403,9 @@ int dev_pm_qos_remove_notifier(struct device *dev,
struct notifier_block *notifier) struct notifier_block *notifier)
{ {
int retval = 0; int retval = 0;
unsigned long flags;
mutex_lock(&dev_pm_qos_mtx); spin_lock_irqsave(&dev_pm_qos_lock, flags);
/* Silently return if the constraints object is not present. */ /* Silently return if the constraints object is not present. */
if (dev->power.constraints) if (dev->power.constraints)
@ -398,7 +413,7 @@ int dev_pm_qos_remove_notifier(struct device *dev,
dev->power.constraints->notifiers, dev->power.constraints->notifiers,
notifier); notifier);
mutex_unlock(&dev_pm_qos_mtx); spin_unlock_irqrestore(&dev_pm_qos_lock, flags);
return retval; return retval;
} }
EXPORT_SYMBOL_GPL(dev_pm_qos_remove_notifier); EXPORT_SYMBOL_GPL(dev_pm_qos_remove_notifier);