On Tue, 11 May 2010 16:20:41 +0200 Andrej Gelenberg <andrej.gelenberg@xxxxxxx> wrote: > Wrap store_scaling_governor with mutex lock cpufreq_governor_mutex. > Fix kernel panic if switch scaling governor very fast. > Bug in bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=15948 > Looks sane, I guess. I am afraid of moving all those functions inside cpufreq_governor_mutex. Not for any specific reason, apart from a long history of nasty deadlocks with cpufreq global locks :( Has this change been well-tested with lockdep enabled? > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > index 75d293e..6ba42f9 100644 > --- a/drivers/cpufreq/cpufreq.c > +++ b/drivers/cpufreq/cpufreq.c > @@ -403,8 +403,6 @@ static int cpufreq_parse_governor(char > *str_governor, unsigned int *policy, > } else if (cpufreq_driver->target) { > struct cpufreq_governor *t; > > - mutex_lock(&cpufreq_governor_mutex); > - > t = __find_governor(str_governor); > > if (t == NULL) { > @@ -429,8 +427,6 @@ static int cpufreq_parse_governor(char > *str_governor, unsigned int *policy, > *governor = t; > err = 0; > } > - > - mutex_unlock(&cpufreq_governor_mutex); > } > out: > return err; > @@ -521,7 +517,7 @@ static ssize_t show_scaling_governor(struct > cpufreq_policy *policy, char *buf) > /** > * store_scaling_governor - store policy for the specified CPU > */ > -static ssize_t store_scaling_governor(struct cpufreq_policy *policy, > +static ssize_t _store_scaling_governor(struct cpufreq_policy *policy, > const char *buf, size_t count) > { > unsigned int ret = -EINVAL; > @@ -553,6 +549,16 @@ static ssize_t store_scaling_governor(struct > cpufreq_policy *policy, > return count; > } > > +static ssize_t store_scaling_governor(struct cpufreq_policy *policy, > + const char *buf, size_t count) > +{ > + ssize_t ret; > + mutex_lock(&cpufreq_governor_mutex); > + ret = _store_scaling_governor(policy, buf, count); > + mutex_unlock(&cpufreq_governor_mutex); > + return ret; > +} > + > /** > * show_scaling_driver - show the cpufreq driver currently loaded > */ Your email client replaces tabs with spaces and is wordwrapping the text. I fixed that up in my copy of the patch. -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
