diff options
| author | Fabio Baltieri <fabio.baltieri@linaro.org> | 2012-11-26 22:10:12 +0400 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2012-11-27 17:11:19 +0400 |
| commit | 3e33ee9e0804748f1b7a01af9ba0e8e1e10f772f (patch) | |
| tree | c92467d4430a9aa941cbc638a3756e04a3ec2112 /drivers/cpufreq | |
| parent | 420993221175a45db5af012c53fd2fef4d9533dc (diff) | |
| download | linux-3e33ee9e0804748f1b7a01af9ba0e8e1e10f772f.tar.xz | |
cpufreq: ondemand: update sampling rate only on right CPUs
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>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpufreq')
| -rw-r--r-- | drivers/cpufreq/cpufreq_ondemand.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c index cca3e9fee9a7..7731f7c7e79a 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); |