Messages in this thread | | | Date | Tue, 12 Jan 2016 15:26:01 +0000 | From | Juri Lelli <> | Subject | Re: [RFC PATCH 04/19] cpufreq: bring data structures close to their locks |
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On 12/01/16 12:36, Juri Lelli wrote: > On 12/01/16 12:58, Peter Zijlstra wrote: > > On Tue, Jan 12, 2016 at 11:21:25AM +0000, Juri Lelli wrote: > > > I tried to see if something like for_each_domain() can be done, but here > > > we use list_for_each_entry() macro. Peter, do you mean something like > > > the following? > > > > > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > > > index 78b1e2f..1a847a6 100644 > > > --- a/drivers/cpufreq/cpufreq.c > > > +++ b/drivers/cpufreq/cpufreq.c > > > @@ -39,6 +39,7 @@ > > > static LIST_HEAD(cpufreq_governor_list); > > > static DEFINE_MUTEX(cpufreq_governor_mutex); > > > #define for_each_governor(__governor) \ > > > + lockdep_assert_held(&cpufreq_governor_mutex); \ > > > list_for_each_entry(__governor, &cpufreq_governor_list, governor_list) > > > > That fails for things like: > > > > if (blah) > > for_each_governor(...) { > > } > > > > which looks like valid C -- even though our Coding Style says the if > > should have { } on. > > > > I was thinking of either open coding the for statement and adding it to > > the first statement like: > > > > #define for_each_governor(__g) \ > > for (_g = list_first_entry(&cpufreq_governor_list, typeof(*_g), governor_list, lockdep_assert_held(), \ > > ..... ) > > > > Or use something like this: > > > > lkml.kernel.org/r/20150422154212.GE3007@worktop.Skamania.guest > > > > #define for_each_governor(_g) \ > > list_for_each_entry(_g, &cpufreq_governor_list, governor_list) > > if (lockdep_assert_held(..), false) > > ; > > else > > > > Which should preserve C syntax rules. > > > > Oh, nice this! I'll try it. >
This second approach doesn't really play well with lockdep_assert_held definition, right?
However, it seems I could make this work with
#ifdef CONFIG_LOCKDEP #define for_each_governor(__gov) \ for (__gov = list_first_entry(&cpufreq_governor_list, \ typeof(*__gov), \ governor_list), \ WARN_ON(debug_locks && \ !lockdep_is_held(&cpufreq_governor_mutex)); \ &__gov->governor_list != (&cpufreq_governor_list); \ __gov = list_next_entry(__gov, governor_list)) #else /* !CONFIG_LOCKDEP */ #define for_each_governor(__gov) \ list_for_each_entry(__gov, &cpufreq_governor_list, governor_list) #endif /* CONFIG_LOCKDEP */
Thanks,
- Juri
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