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Subject[RFC][PATCH 3/7]: notifier_head changes with removal of reducdant protection
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Date
This patch includes changes to notifier chain head definitions and removal
of additional protection that is no longer needed.

Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
-----
drivers/cpufreq/cpufreq.c | 19 +++----------------
kernel/cpu.c | 12 ++----------
kernel/module.c | 17 +++--------------
kernel/profile.c | 35 +++++------------------------------
4 files changed, 13 insertions(+), 70 deletions(-)
Index: l2615-rc1-notifiers/drivers/cpufreq/cpufreq.c
===================================================================
--- l2615-rc1-notifiers.orig/drivers/cpufreq/cpufreq.c
+++ l2615-rc1-notifiers/drivers/cpufreq/cpufreq.c
@@ -50,9 +50,8 @@ static inline void adjust_jiffies(unsign
* changes to devices when the CPU clock speed changes.
* The mutex locks both lists.
*/
-static struct notifier_block *cpufreq_policy_notifier_list;
-static struct notifier_block *cpufreq_transition_notifier_list;
-static DECLARE_RWSEM (cpufreq_notifier_rwsem);
+static BLOCKING_NOTIFIER_HEAD(cpufreq_policy_notifier_list);
+static BLOCKING_NOTIFIER_HEAD(cpufreq_transition_notifier_list);


static LIST_HEAD(cpufreq_governor_list);
@@ -241,7 +240,6 @@ void cpufreq_notify_transition(struct cp
freqs->flags = cpufreq_driver->flags;
dprintk("notification %u of frequency transition to %u kHz\n", state, freqs->new);

- down_read(&cpufreq_notifier_rwsem);
switch (state) {
case CPUFREQ_PRECHANGE:
/* detect if the driver reported a value as "old frequency" which
@@ -269,7 +267,6 @@ void cpufreq_notify_transition(struct cp
cpufreq_cpu_data[freqs->cpu]->cur = freqs->new;
break;
}
- up_read(&cpufreq_notifier_rwsem);
}
EXPORT_SYMBOL_GPL(cpufreq_notify_transition);

@@ -1052,7 +1049,6 @@ int cpufreq_register_notifier(struct not
{
int ret;

- down_write(&cpufreq_notifier_rwsem);
switch (list) {
case CPUFREQ_TRANSITION_NOTIFIER:
ret = notifier_chain_register(&cpufreq_transition_notifier_list, nb);
@@ -1063,7 +1059,6 @@ int cpufreq_register_notifier(struct not
default:
ret = -EINVAL;
}
- up_write(&cpufreq_notifier_rwsem);

return ret;
}
@@ -1084,7 +1079,6 @@ int cpufreq_unregister_notifier(struct n
{
int ret;

- down_write(&cpufreq_notifier_rwsem);
switch (list) {
case CPUFREQ_TRANSITION_NOTIFIER:
ret = notifier_chain_unregister(&cpufreq_transition_notifier_list, nb);
@@ -1095,7 +1089,6 @@ int cpufreq_unregister_notifier(struct n
default:
ret = -EINVAL;
}
- up_write(&cpufreq_notifier_rwsem);

return ret;
}
@@ -1281,8 +1274,6 @@ static int __cpufreq_set_policy(struct c
if (ret)
goto error_out;

- down_read(&cpufreq_notifier_rwsem);
-
/* adjust if necessary - all reasons */
notifier_call_chain(&cpufreq_policy_notifier_list, CPUFREQ_ADJUST,
policy);
@@ -1294,17 +1285,13 @@ static int __cpufreq_set_policy(struct c
/* verify the cpu speed can be set within this limit,
which might be different to the first one */
ret = cpufreq_driver->verify(policy);
- if (ret) {
- up_read(&cpufreq_notifier_rwsem);
+ if (ret)
goto error_out;
- }

/* notification of the new policy */
notifier_call_chain(&cpufreq_policy_notifier_list, CPUFREQ_NOTIFY,
policy);

- up_read(&cpufreq_notifier_rwsem);
-
data->min = policy->min;
data->max = policy->max;

Index: l2615-rc1-notifiers/kernel/cpu.c
===================================================================
--- l2615-rc1-notifiers.orig/kernel/cpu.c
+++ l2615-rc1-notifiers/kernel/cpu.c
@@ -19,7 +19,7 @@
DECLARE_MUTEX(cpucontrol);
EXPORT_SYMBOL_GPL(cpucontrol);

-static struct notifier_block *cpu_chain;
+static BLOCKING_NOTIFIER_HEAD(cpu_chain);

/*
* Used to check by callers if they need to acquire the cpucontrol
@@ -42,21 +42,13 @@ EXPORT_SYMBOL_GPL(current_in_cpu_hotplug
/* Need to know about CPUs going up/down? */
int register_cpu_notifier(struct notifier_block *nb)
{
- int ret;
-
- if ((ret = down_interruptible(&cpucontrol)) != 0)
- return ret;
- ret = notifier_chain_register(&cpu_chain, nb);
- up(&cpucontrol);
- return ret;
+ return notifier_chain_register(&cpu_chain, nb);
}
EXPORT_SYMBOL(register_cpu_notifier);

void unregister_cpu_notifier(struct notifier_block *nb)
{
- down(&cpucontrol);
notifier_chain_unregister(&cpu_chain, nb);
- up(&cpucontrol);
}
EXPORT_SYMBOL(unregister_cpu_notifier);

Index: l2615-rc1-notifiers/kernel/module.c
===================================================================
--- l2615-rc1-notifiers.orig/kernel/module.c
+++ l2615-rc1-notifiers/kernel/module.c
@@ -62,26 +62,17 @@ static DEFINE_SPINLOCK(modlist_lock);
static DECLARE_MUTEX(module_mutex);
static LIST_HEAD(modules);

-static DECLARE_MUTEX(notify_mutex);
-static struct notifier_block * module_notify_list;
+static BLOCKING_NOTIFIER_HEAD(module_notify_list);

int register_module_notifier(struct notifier_block * nb)
{
- int err;
- down(&notify_mutex);
- err = notifier_chain_register(&module_notify_list, nb);
- up(&notify_mutex);
- return err;
+ return notifier_chain_register(&module_notify_list, nb);
}
EXPORT_SYMBOL(register_module_notifier);

int unregister_module_notifier(struct notifier_block * nb)
{
- int err;
- down(&notify_mutex);
- err = notifier_chain_unregister(&module_notify_list, nb);
- up(&notify_mutex);
- return err;
+ return notifier_chain_unregister(&module_notify_list, nb);
}
EXPORT_SYMBOL(unregister_module_notifier);

@@ -1905,9 +1896,7 @@ sys_init_module(void __user *umod,
/* Drop lock so they can recurse */
up(&module_mutex);

- down(&notify_mutex);
notifier_call_chain(&module_notify_list, MODULE_STATE_COMING, mod);
- up(&notify_mutex);

/* Start the module */
if (mod->init != NULL)
Index: l2615-rc1-notifiers/kernel/profile.c
===================================================================
--- l2615-rc1-notifiers.orig/kernel/profile.c
+++ l2615-rc1-notifiers/kernel/profile.c
@@ -86,61 +86,41 @@ void __init profile_init(void)

#ifdef CONFIG_PROFILING

-static DECLARE_RWSEM(profile_rwsem);
-static DEFINE_RWLOCK(handoff_lock);
-static struct notifier_block * task_exit_notifier;
-static struct notifier_block * task_free_notifier;
-static struct notifier_block * munmap_notifier;
+static BLOCKING_NOTIFIER_HEAD(task_exit_notifier);
+static ATOMIC_NOTIFIER_HEAD(task_free_notifier);
+static BLOCKING_NOTIFIER_HEAD(munmap_notifier);

void profile_task_exit(struct task_struct * task)
{
- down_read(&profile_rwsem);
notifier_call_chain(&task_exit_notifier, 0, task);
- up_read(&profile_rwsem);
}

int profile_handoff_task(struct task_struct * task)
{
int ret;
- read_lock(&handoff_lock);
ret = notifier_call_chain(&task_free_notifier, 0, task);
- read_unlock(&handoff_lock);
return (ret == NOTIFY_OK) ? 1 : 0;
}

void profile_munmap(unsigned long addr)
{
- down_read(&profile_rwsem);
notifier_call_chain(&munmap_notifier, 0, (void *)addr);
- up_read(&profile_rwsem);
}

int task_handoff_register(struct notifier_block * n)
{
- int err = -EINVAL;
-
- write_lock(&handoff_lock);
- err = notifier_chain_register(&task_free_notifier, n);
- write_unlock(&handoff_lock);
- return err;
+ return notifier_chain_register(&task_free_notifier, n);
}

int task_handoff_unregister(struct notifier_block * n)
{
- int err = -EINVAL;
-
- write_lock(&handoff_lock);
- err = notifier_chain_unregister(&task_free_notifier, n);
- write_unlock(&handoff_lock);
- return err;
+ return notifier_chain_unregister(&task_free_notifier, n);
}

int profile_event_register(enum profile_type type, struct notifier_block * n)
{
int err = -EINVAL;

- down_write(&profile_rwsem);
-
switch (type) {
case PROFILE_TASK_EXIT:
err = notifier_chain_register(&task_exit_notifier, n);
@@ -150,8 +130,6 @@ int profile_event_register(enum profile_
break;
}

- up_write(&profile_rwsem);
-
return err;
}

@@ -160,8 +138,6 @@ int profile_event_unregister(enum profil
{
int err = -EINVAL;

- down_write(&profile_rwsem);
-
switch (type) {
case PROFILE_TASK_EXIT:
err = notifier_chain_unregister(&task_exit_notifier, n);
@@ -171,7 +147,6 @@ int profile_event_unregister(enum profil
break;
}

- up_write(&profile_rwsem);
return err;
}

--

----------------------------------------------------------------------
Chandra Seetharaman | Be careful what you choose....
- sekharan@us.ibm.com | .......you may get it.
----------------------------------------------------------------------

-
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