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| author | Alan Stern <stern@rowland.harvard.edu> | 2006-10-04 02:17:06 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-10-04 07:55:30 -0700 |
| commit | b4dfdbb3c707474a2254c5b4d7e62be31a4b7da9 (patch) | |
| tree | 20558266428cb904c4ffc660647cfdb7e7abeae5 | |
| parent | e6a92013ba458804161c0c5b6d134d82204dc233 (diff) | |
| download | linux-b4dfdbb3c707474a2254c5b4d7e62be31a4b7da9.tar.gz linux-b4dfdbb3c707474a2254c5b4d7e62be31a4b7da9.tar.bz2 linux-b4dfdbb3c707474a2254c5b4d7e62be31a4b7da9.zip | |
[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>
| -rw-r--r-- | drivers/cpufreq/cpufreq.c | 20 |
1 files changed, 13 insertions, 7 deletions
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 2caaf71d80c8..86e69b7f9122 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: |