| Message ID | 1353953412-20667-1-git-send-email-fabio.baltieri@linaro.org (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Headers | show |
On Monday, November 26, 2012 07:10:12 PM Fabio Baltieri wrote: > Fix cpufreq_gov_ondemand to skip CPU where another governor is used. > > The bug present itself as NULL pointer access on the mutex_lock() call, > an can be reproduced on an SMP machine by setting the default governor > to anything other than ondemand, setting a single CPU's governor to > ondemand, then changing the sample rate by writing on: > > > /sys/devices/system/cpu/cpufreq/ondemand/sampling_rate > > Backtrace: > > Nov 26 17:36:54 balto kernel: [ 839.585241] BUG: unable to handle kernel NULL pointer dereference at (null) > Nov 26 17:36:54 balto kernel: [ 839.585311] IP: [<ffffffff8174e082>] __mutex_lock_slowpath+0xb2/0x170 > [snip] > Nov 26 17:36:54 balto kernel: [ 839.587005] Call Trace: > Nov 26 17:36:54 balto kernel: [ 839.587030] [<ffffffff8174da82>] mutex_lock+0x22/0x40 > Nov 26 17:36:54 balto kernel: [ 839.587067] [<ffffffff81610b8f>] store_sampling_rate+0xbf/0x150 > Nov 26 17:36:54 balto kernel: [ 839.587110] [<ffffffff81031e9c>] ? __do_page_fault+0x1cc/0x4c0 > Nov 26 17:36:54 balto kernel: [ 839.587153] [<ffffffff813309bf>] kobj_attr_store+0xf/0x20 > Nov 26 17:36:54 balto kernel: [ 839.587192] [<ffffffff811bb62d>] sysfs_write_file+0xcd/0x140 > Nov 26 17:36:54 balto kernel: [ 839.587234] [<ffffffff8114c12c>] vfs_write+0xac/0x180 > Nov 26 17:36:54 balto kernel: [ 839.587271] [<ffffffff8114c472>] sys_write+0x52/0xa0 > Nov 26 17:36:54 balto kernel: [ 839.587306] [<ffffffff810321ce>] ? do_page_fault+0xe/0x10 > Nov 26 17:36:54 balto kernel: [ 839.587345] [<ffffffff81751202>] system_call_fastpath+0x16/0x1b > > Signed-off-by: Fabio Baltieri <fabio.baltieri@linaro.org> > --- > > Hi Rafael, > > this is based on a clean linux-pm linux-next branch (i.e. not with my other > patch-set applied), so expect a context conflict if both are applied. I have applied this patch to my linux-next branch. As for the other series, I'm in the process of reviewing it, but I rather won't include it into my first pull request for v3.8. Thanks, Rafael > drivers/cpufreq/cpufreq_ondemand.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c > index cca3e9f..7731f7c 100644 > --- a/drivers/cpufreq/cpufreq_ondemand.c > +++ b/drivers/cpufreq/cpufreq_ondemand.c > @@ -40,6 +40,10 @@ > static struct dbs_data od_dbs_data; > static DEFINE_PER_CPU(struct od_cpu_dbs_info_s, od_cpu_dbs_info); > > +#ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND > +static struct cpufreq_governor cpufreq_gov_ondemand; > +#endif > + > static struct od_dbs_tuners od_tuners = { > .up_threshold = DEF_FREQUENCY_UP_THRESHOLD, > .sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR, > @@ -279,6 +283,10 @@ static void update_sampling_rate(unsigned int new_rate) > policy = cpufreq_cpu_get(cpu); > if (!policy) > continue; > + if (policy->governor != &cpufreq_gov_ondemand) { > + cpufreq_cpu_put(policy); > + continue; > + } > dbs_info = &per_cpu(od_cpu_dbs_info, policy->cpu); > cpufreq_cpu_put(policy); > >
diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c index cca3e9f..7731f7c 100644 --- a/drivers/cpufreq/cpufreq_ondemand.c +++ b/drivers/cpufreq/cpufreq_ondemand.c @@ -40,6 +40,10 @@ static struct dbs_data od_dbs_data; static DEFINE_PER_CPU(struct od_cpu_dbs_info_s, od_cpu_dbs_info); +#ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND +static struct cpufreq_governor cpufreq_gov_ondemand; +#endif + static struct od_dbs_tuners od_tuners = { .up_threshold = DEF_FREQUENCY_UP_THRESHOLD, .sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR, @@ -279,6 +283,10 @@ static void update_sampling_rate(unsigned int new_rate) policy = cpufreq_cpu_get(cpu); if (!policy) continue; + if (policy->governor != &cpufreq_gov_ondemand) { + cpufreq_cpu_put(policy); + continue; + } dbs_info = &per_cpu(od_cpu_dbs_info, policy->cpu); cpufreq_cpu_put(policy);