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cpufreq: Preserve sysfs files across suspend/resume

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The file permissions of cpufreq per-cpu sysfs files are not preserved
across suspend/resume because we internally go through the CPU
Hotplug path which reinitializes the file permissions on CPU online.

But the user is not supposed to know that we are using CPU hotplug
internally within suspend/resume (IOW, the kernel should not silently
wreck the user-set file permissions across a suspend cycle).
Therefore, we need to preserve the file permissions as they are
across suspend/resume.

The simplest way to achieve that is to just not touch the sysfs files
at all - ie., just ignore the CPU hotplug notifications in the
suspend/resume path (_FROZEN) in the cpufreq hotplug callback.

Reported-by: Robert Jarzmik <robert.jarzmik@intel.com>
Reported-by: Durgadoss R <durgadoss.r@intel.com>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Srivatsa S. Bhat 2013-05-15 21:47:17 +02:00 committed by Rafael J. Wysocki
parent b57ffac5e5
commit a66b2e503f
2 changed files with 5 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
drivers/cpufreq/cpufreq.c
View File

@ -1832,15 +1832,13 @@ static int __cpuinit cpufreq_cpu_callback(struct notifier_block *nfb,
if (dev) {
switch (action) {
case CPU_ONLINE:
case CPU_ONLINE_FROZEN:
cpufreq_add_dev(dev, NULL);
break;
case CPU_DOWN_PREPARE:
case CPU_DOWN_PREPARE_FROZEN:
case CPU_UP_CANCELED_FROZEN:
__cpufreq_remove_dev(dev, NULL);
break;
case CPU_DOWN_FAILED:
case CPU_DOWN_FAILED_FROZEN:
cpufreq_add_dev(dev, NULL);
break;
}

7
drivers/cpufreq/cpufreq_stats.c
View File

@ -349,15 +349,16 @@ static int __cpuinit cpufreq_stat_cpu_callback(struct notifier_block *nfb,
switch (action) {
case CPU_ONLINE:
case CPU_ONLINE_FROZEN:
cpufreq_update_policy(cpu);
break;
case CPU_DOWN_PREPARE:
case CPU_DOWN_PREPARE_FROZEN:
cpufreq_stats_free_sysfs(cpu);
break;
case CPU_DEAD:
case CPU_DEAD_FROZEN:
cpufreq_stats_free_table(cpu);
break;
case CPU_UP_CANCELED_FROZEN:
cpufreq_stats_free_sysfs(cpu);
cpufreq_stats_free_table(cpu);
break;
}