Prev: [PATCH 2/2] [RFC] pm_qos: add atomic notifier chain
Next: i2c: Single-wire Serial Bus Interface for Qualcomm MSM chipsets
From: florian on 23 Jul 2010 06:10
In order to allow drivers to use pm_qos_update_request from interrupt
context we check for interrupt context via in_interrupt() and call
the notifiers via schedule_work() if need be.

There is the following semantic difference between update_request call
sites that are in interrupt context and process context:
If the notification-work is already scheduled then schedule_work might be a
noop. In order to avoid buffering of all intermediary constraint-values we
query the current value at notification time. This means that for constraints
updated from interrupt-context the listeners might only see the last value.

This also adds some WARN's to check for invalid class-descriptors as
input params of exported functions and substitutes the pointer-array
pm_qos_array with an array of structs (pm_qos_objects).
The latter is needed to get at the array-index of a pm_qos_object-pointer.

Also adding new qos-classes should be easier now, as one needs to only
extend the pm_qos_classes enum in the header and initialize the pm_qos_object
in the implementation file.

Signed-off-by: Florian Mickler <florian(a)mickler.org>
---
include/linux/pm_qos_params.h | 12 ++-
kernel/pm_qos_params.c | 202 ++++++++++++++++++++++++++---------------
2 files changed, 135 insertions(+), 79 deletions(-)

diff --git a/include/linux/pm_qos_params.h b/include/linux/pm_qos_params.h
index 77cbddb..fdd8a78 100644
--- a/include/linux/pm_qos_params.h
+++ b/include/linux/pm_qos_params.h
@@ -8,12 +8,14 @@
#include <linux/notifier.h>
#include <linux/miscdevice.h>

-#define PM_QOS_RESERVED 0
-#define PM_QOS_CPU_DMA_LATENCY 1
-#define PM_QOS_NETWORK_LATENCY 2
-#define PM_QOS_NETWORK_THROUGHPUT 3
+enum pm_qos_classes {
+ PM_QOS_RESERVED = 0,
+ PM_QOS_CPU_DMA_LATENCY,
+ PM_QOS_NETWORK_LATENCY,
+ PM_QOS_NETWORK_THROUGHPUT,
+ PM_QOS_NUM_CLASSES
+};

-#define PM_QOS_NUM_CLASSES 4
#define PM_QOS_DEFAULT_VALUE -1

struct pm_qos_request_list {
diff --git a/kernel/pm_qos_params.c b/kernel/pm_qos_params.c
index 996a4de..640c367 100644
--- a/kernel/pm_qos_params.c
+++ b/kernel/pm_qos_params.c
@@ -29,19 +29,20 @@

/*#define DEBUG*/

+#include <linux/platform_device.h>
#include <linux/pm_qos_params.h>
-#include <linux/sched.h>
+#include <linux/miscdevice.h>
+#include <linux/workqueue.h>
#include <linux/spinlock.h>
-#include <linux/slab.h>
-#include <linux/time.h>
-#include <linux/fs.h>
+#include <linux/hardirq.h>
+#include <linux/uaccess.h>
#include <linux/device.h>
-#include <linux/miscdevice.h>
#include <linux/string.h>
-#include <linux/platform_device.h>
+#include <linux/sched.h>
#include <linux/init.h>
-
-#include <linux/uaccess.h>
+#include <linux/slab.h>
+#include <linux/time.h>
+#include <linux/fs.h>

/*
* locking rule: all changes to requests or notifiers lists
@@ -55,50 +56,65 @@ enum pm_qos_type {

struct pm_qos_object {
struct plist_head requests;
- struct blocking_notifier_head *notifiers;
+ struct blocking_notifier_head notifiers;
struct miscdevice pm_qos_power_miscdev;
+ struct work_struct notify;
char *name;
s32 default_value;
enum pm_qos_type type;
};

static DEFINE_SPINLOCK(pm_qos_lock);
-
-static struct pm_qos_object null_pm_qos;
-static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier);
-static struct pm_qos_object cpu_dma_pm_qos = {
- .requests = PLIST_HEAD_INIT(cpu_dma_pm_qos.requests, pm_qos_lock),
- .notifiers = &cpu_dma_lat_notifier,
- .name = "cpu_dma_latency",
- .default_value = 2000 * USEC_PER_SEC,
- .type = PM_QOS_MIN,
-};
-
-static BLOCKING_NOTIFIER_HEAD(network_lat_notifier);
-static struct pm_qos_object network_lat_pm_qos = {
- .requests = PLIST_HEAD_INIT(network_lat_pm_qos.requests, pm_qos_lock),
- .notifiers = &network_lat_notifier,
- .name = "network_latency",
- .default_value = 2000 * USEC_PER_SEC,
- .type = PM_QOS_MIN
-};
-
-
-static BLOCKING_NOTIFIER_HEAD(network_throughput_notifier);
-static struct pm_qos_object network_throughput_pm_qos = {
- .requests = PLIST_HEAD_INIT(network_throughput_pm_qos.requests, pm_qos_lock),
- .notifiers = &network_throughput_notifier,
- .name = "network_throughput",
- .default_value = 0,
- .type = PM_QOS_MAX,
-};
-
-
-static struct pm_qos_object *pm_qos_array[] = {
- &null_pm_qos,
- &cpu_dma_pm_qos,
- &network_lat_pm_qos,
- &network_throughput_pm_qos
+static void update_notify(struct work_struct *work);
+
+/* see pm_qos_classes enum in the header */
+static struct pm_qos_object pm_qos_objects[] = {
+ {}, /* PM_QOS_RESERVED */
+ {
+ .requests = PLIST_HEAD_INIT(
+ pm_qos_objects[PM_QOS_CPU_DMA_LATENCY].requests,
+ pm_qos_lock),
+ .notifiers = BLOCKING_NOTIFIER_INIT(
+ pm_qos_objects[PM_QOS_CPU_DMA_LATENCY].notifiers),
+ .notify = __WORK_INITIALIZER(
+ pm_qos_objects[PM_QOS_CPU_DMA_LATENCY].notify,
+ update_notify),
+ .name = "cpu_dma_latency",
+ .default_value = 2000 * USEC_PER_SEC,
+ .type = PM_QOS_MIN,
+ }, /* PM_QOS_CPU_DMA_LATENCY */
+ {
+ .requests = PLIST_HEAD_INIT(
+ pm_qos_objects[PM_QOS_NETWORK_LATENCY].requests,
+ pm_qos_lock
+ ),
+ .notifiers = BLOCKING_NOTIFIER_INIT(
+ pm_qos_objects[PM_QOS_NETWORK_LATENCY].notifiers
+ ),
+ .notify = __WORK_INITIALIZER(
+ pm_qos_objects[PM_QOS_NETWORK_LATENCY].notify,
+ update_notify
+ ),
+ .name = "network_latency",
+ .default_value = 2000 * USEC_PER_SEC,
+ .type = PM_QOS_MIN
+ }, /* PM_QOS_NETWORK_LATENCY */
+ {
+ .requests = PLIST_HEAD_INIT(
+ pm_qos_objects[PM_QOS_NETWORK_THROUGHPUT].requests,
+ pm_qos_lock
+ ),
+ .notifiers = BLOCKING_NOTIFIER_INIT(
+ pm_qos_objects[PM_QOS_NETWORK_THROUGHPUT].notifiers
+ ),
+ .notify = __WORK_INITIALIZER(
+ pm_qos_objects[PM_QOS_NETWORK_THROUGHPUT].notify,
+ update_notify
+ ),
+ .name = "network_throughput",
+ .default_value = 0,
+ .type = PM_QOS_MAX,
+ }, /* PM_QOS_NETWORK_THROUGHPUT */
};

static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
@@ -131,6 +147,30 @@ static inline int pm_qos_get_value(struct pm_qos_object *o)
}
}

+static void call_notifiers(struct pm_qos_object *o, unsigned long val)
+{
+
+ if (in_interrupt())
+ schedule_work(&o->notify);
+ else
+ blocking_notifier_call_chain(&o->notifiers, val,
+ NULL);
+
+
+}
+
+/* This is the work function that gets scheduled
+ * in call_notifiers if necessary. */
+static void update_notify(struct work_struct *work)
+{
+ struct pm_qos_object *obj =
+ container_of(work, struct pm_qos_object, notify);
+
+ int extreme_value = pm_qos_request(obj - pm_qos_objects);
+ blocking_notifier_call_chain(&obj->notifiers,
+ (unsigned long) extreme_value, NULL);
+}
+
static void update_target(struct pm_qos_object *o, struct plist_node *node,
int del, int value)
{
@@ -158,9 +198,7 @@ static void update_target(struct pm_qos_object *o, struct plist_node *node,
spin_unlock_irqrestore(&pm_qos_lock, flags);

if (prev_value != curr_value)
- blocking_notifier_call_chain(o->notifiers,
- (unsigned long)curr_value,
- NULL);
+ call_notifiers(o, (unsigned long) curr_value);
}

static int register_pm_qos_misc(struct pm_qos_object *qos)
@@ -179,12 +217,17 @@ static int find_pm_qos_object_by_minor(int minor)
for (pm_qos_class = 0;
pm_qos_class < PM_QOS_NUM_CLASSES; pm_qos_class++) {
if (minor ==
- pm_qos_array[pm_qos_class]->pm_qos_power_miscdev.minor)
+ pm_qos_objects[pm_qos_class].pm_qos_power_miscdev.minor)
return pm_qos_class;
}
return -1;
}

+int pm_qos_valid_class(int pm_qos_class)
+{
+ return pm_qos_class > 0 && pm_qos_class < PM_QOS_NUM_CLASSES;
+}
+
/**
* pm_qos_request - returns current system wide qos expectation
* @pm_qos_class: identification of which qos value is requested
@@ -196,8 +239,13 @@ int pm_qos_request(int pm_qos_class)
unsigned long flags;
int value;

+ if (!pm_qos_valid_class(pm_qos_class)) {
+ WARN(1, KERN_ERR "pm_qos_request() called for unknown qos class\n");
+ return -EINVAL;
+ }
+
spin_lock_irqsave(&pm_qos_lock, flags);
- value = pm_qos_get_value(pm_qos_array[pm_qos_class]);
+ value = pm_qos_get_value(&pm_qos_objects[pm_qos_class]);
spin_unlock_irqrestore(&pm_qos_lock, flags);

return value;
@@ -206,7 +254,7 @@ EXPORT_SYMBOL_GPL(pm_qos_request);

int pm_qos_request_active(struct pm_qos_request_list *req)
{
- return req->pm_qos_class != 0;
+ return req && pm_qos_valid_class(req->pm_qos_class);
}
EXPORT_SYMBOL_GPL(pm_qos_request_active);

@@ -224,9 +272,16 @@ EXPORT_SYMBOL_GPL(pm_qos_request_active);
void pm_qos_add_request(struct pm_qos_request_list *dep,
int pm_qos_class, s32 value)
{
- struct pm_qos_object *o = pm_qos_array[pm_qos_class];
+ struct pm_qos_object *o;
int new_value;

+ if (!pm_qos_valid_class(pm_qos_class)) {
+ WARN(1, KERN_ERR "pm_qos_add_request() called for unknown qos class\n");
+ return;
+ }
+
+ o = &pm_qos_objects[pm_qos_class];
+
if (pm_qos_request_active(dep)) {
WARN(1, KERN_ERR "pm_qos_add_request() called for already added request\n");
return;
@@ -261,11 +316,11 @@ void pm_qos_update_request(struct pm_qos_request_list *pm_qos_req,
return;

if (!pm_qos_request_active(pm_qos_req)) {
- WARN(1, KERN_ERR "pm_qos_update_request() called for unknown object\n");
+ WARN(1, KERN_ERR "pm_qos_update_request() called for unknown request object\n");
return;
}

- o = pm_qos_array[pm_qos_req->pm_qos_class];
+ o = &pm_qos_objects[pm_qos_req->pm_qos_class];

if (new_value == PM_QOS_DEFAULT_VALUE)
temp = o->default_value;
@@ -298,7 +353,7 @@ void pm_qos_remove_request(struct pm_qos_request_list *pm_qos_req)
return;
}

- o = pm_qos_array[pm_qos_req->pm_qos_class];
+ o = &pm_qos_objects[pm_qos_req->pm_qos_class];
update_target(o, &pm_qos_req->list, 1, PM_QOS_DEFAULT_VALUE);
memset(pm_qos_req, 0, sizeof(*pm_qos_req));
}
@@ -309,15 +364,18 @@ EXPORT_SYMBOL_GPL(pm_qos_remove_request);
* @pm_qos_class: identifies which qos target changes should be notified.
* @notifier: notifier block managed by caller.
*
- * will register the notifier into a notification chain that gets called
+ * Will register the notifier into a notification chain that gets called
* upon changes to the pm_qos_class target value.
*/
int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)
{
int retval;
-
+ if (!pm_qos_valid_class(pm_qos_class)) {
+ WARN(1, KERN_ERR "pm_qos_add_notifier called for unknown qos class\n");
+ return -EINVAL;
+ }
retval = blocking_notifier_chain_register(
- pm_qos_array[pm_qos_class]->notifiers, notifier);
+ &pm_qos_objects[pm_qos_class].notifiers, notifier);

return retval;
}
@@ -328,15 +386,19 @@ EXPORT_SYMBOL_GPL(pm_qos_add_notifier);
* @pm_qos_class: identifies which qos target changes are notified.
* @notifier: notifier block to be removed.
*
- * will remove the notifier from the notification chain that gets called
+ * Will remove the notifier from the notification chain that gets called
* upon changes to the pm_qos_class target value.
*/
int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier)
{
int retval;
+ if (!pm_qos_valid_class(pm_qos_class)) {
+ WARN(1, KERN_ERR "pm_qos_remove_notifier called for unknown qos class\n");
+ return -EINVAL;
+ }

retval = blocking_notifier_chain_unregister(
- pm_qos_array[pm_qos_class]->notifiers, notifier);
+ &pm_qos_objects[pm_qos_class].notifiers, notifier);

return retval;
}
@@ -404,21 +466,13 @@ static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
static int __init pm_qos_power_init(void)
{
int ret = 0;
+ int qos_class;

- ret = register_pm_qos_misc(&cpu_dma_pm_qos);
- if (ret < 0) {
- printk(KERN_ERR "pm_qos_param: cpu_dma_latency setup failed\n");
- return ret;
- }
- ret = register_pm_qos_misc(&network_lat_pm_qos);
- if (ret < 0) {
- printk(KERN_ERR "pm_qos_param: network_latency setup failed\n");
- return ret;
- }
- ret = register_pm_qos_misc(&network_throughput_pm_qos);
- if (ret < 0)
- printk(KERN_ERR
- "pm_qos_param: network_throughput setup failed\n");
+ for (qos_class = 1; qos_class < PM_QOS_NUM_CLASSES; qos_class++)
+ if (register_pm_qos_misc(&pm_qos_objects[qos_class])) {
+ printk(KERN_ERR "pm_qos_param: setup failed for %s\n", pm_qos_objects[qos_class].name);
+ ret |= 1;
+ }

return ret;
}
--
1.7.1.1

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