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authorAlan Stern <stern@rowland.harvard.edu>2006-10-04 02:17:06 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-10-04 07:55:30 -0700
commitb4dfdbb3c707474a2254c5b4d7e62be31a4b7da9 (patch)
tree20558266428cb904c4ffc660647cfdb7e7abeae5 /drivers
parente6a92013ba458804161c0c5b6d134d82204dc233 (diff)
[PATCH] cpufreq: make the transition_notifier chain use SRCU
This patch (as762) changes the cpufreq_transition_notifier_list from a blocking_notifier_head to an srcu_notifier_head. This will prevent errors caused attempting to call down_read() to access the notifier chain at a time when interrupts must remain disabled, during system suspend. It's not clear to me whether this is really necessary; perhaps the chain could be made into an atomic_notifier. However a couple of the callout routines do use blocking operations, so this approach seems safer. The head of the notifier chain needs to be initialized before use; this is done by an __init routine at core_initcall time. If this turns out not to be a good choice, it can easily be changed. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Cc: Jesse Brandeburg <jesse.brandeburg@gmail.com> Cc: Dave Jones <davej@codemonkey.org.uk> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/cpufreq/cpufreq.c20
1 files changed, 13 insertions, 7 deletions
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 2caaf71d80c..86e69b7f912 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -52,8 +52,14 @@ static void handle_update(void *data);
* The mutex locks both lists.
*/
static BLOCKING_NOTIFIER_HEAD(cpufreq_policy_notifier_list);
-static BLOCKING_NOTIFIER_HEAD(cpufreq_transition_notifier_list);
+static struct srcu_notifier_head cpufreq_transition_notifier_list;
+static int __init init_cpufreq_transition_notifier_list(void)
+{
+ srcu_init_notifier_head(&cpufreq_transition_notifier_list);
+ return 0;
+}
+core_initcall(init_cpufreq_transition_notifier_list);
static LIST_HEAD(cpufreq_governor_list);
static DEFINE_MUTEX (cpufreq_governor_mutex);
@@ -262,14 +268,14 @@ void cpufreq_notify_transition(struct cpufreq_freqs *freqs, unsigned int state)
freqs->old = policy->cur;
}
}
- blocking_notifier_call_chain(&cpufreq_transition_notifier_list,
+ srcu_notifier_call_chain(&cpufreq_transition_notifier_list,
CPUFREQ_PRECHANGE, freqs);
adjust_jiffies(CPUFREQ_PRECHANGE, freqs);
break;
case CPUFREQ_POSTCHANGE:
adjust_jiffies(CPUFREQ_POSTCHANGE, freqs);
- blocking_notifier_call_chain(&cpufreq_transition_notifier_list,
+ srcu_notifier_call_chain(&cpufreq_transition_notifier_list,
CPUFREQ_POSTCHANGE, freqs);
if (likely(policy) && likely(policy->cpu == freqs->cpu))
policy->cur = freqs->new;
@@ -1049,7 +1055,7 @@ static int cpufreq_suspend(struct sys_device * sysdev, pm_message_t pmsg)
freqs.old = cpu_policy->cur;
freqs.new = cur_freq;
- blocking_notifier_call_chain(&cpufreq_transition_notifier_list,
+ srcu_notifier_call_chain(&cpufreq_transition_notifier_list,
CPUFREQ_SUSPENDCHANGE, &freqs);
adjust_jiffies(CPUFREQ_SUSPENDCHANGE, &freqs);
@@ -1130,7 +1136,7 @@ static int cpufreq_resume(struct sys_device * sysdev)
freqs.old = cpu_policy->cur;
freqs.new = cur_freq;
- blocking_notifier_call_chain(
+ srcu_notifier_call_chain(
&cpufreq_transition_notifier_list,
CPUFREQ_RESUMECHANGE, &freqs);
adjust_jiffies(CPUFREQ_RESUMECHANGE, &freqs);
@@ -1176,7 +1182,7 @@ int cpufreq_register_notifier(struct notifier_block *nb, unsigned int list)
switch (list) {
case CPUFREQ_TRANSITION_NOTIFIER:
- ret = blocking_notifier_chain_register(
+ ret = srcu_notifier_chain_register(
&cpufreq_transition_notifier_list, nb);
break;
case CPUFREQ_POLICY_NOTIFIER:
@@ -1208,7 +1214,7 @@ int cpufreq_unregister_notifier(struct notifier_block *nb, unsigned int list)
switch (list) {
case CPUFREQ_TRANSITION_NOTIFIER:
- ret = blocking_notifier_chain_unregister(
+ ret = srcu_notifier_chain_unregister(
&cpufreq_transition_notifier_list, nb);
break;
case CPUFREQ_POLICY_NOTIFIER: