From 3de9bdeb28638e164d1f0eb38dd68e3f5d2ac95c Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Tue, 6 Aug 2013 22:53:13 +0530 Subject: [PATCH] cpufreq: improve error checking on return values of __cpufreq_governor() The __cpufreq_governor() function can fail in rare cases especially if there are bugs in cpufreq drivers. Thus we must stop processing as soon as this routine fails, otherwise it may result in undefined behavior. This patch adds error checking code whenever this routine is called from any place. Signed-off-by: Viresh Kumar Signed-off-by: Rafael J. Wysocki --- drivers/cpufreq/cpufreq.c | 48 +++++++++++++++++++++++++++++++++++------------ 1 file changed, 36 insertions(+), 12 deletions(-) diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index c9bbfee..37a6874 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -874,8 +874,13 @@ static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, int ret = 0, has_target = !!cpufreq_driver->target; unsigned long flags; - if (has_target) - __cpufreq_governor(policy, CPUFREQ_GOV_STOP); + if (has_target) { + ret = __cpufreq_governor(policy, CPUFREQ_GOV_STOP); + if (ret) { + pr_err("%s: Failed to stop governor\n", __func__); + return ret; + } + } lock_policy_rwsem_write(policy->cpu); @@ -889,8 +894,11 @@ static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, unlock_policy_rwsem_write(policy->cpu); if (has_target) { - __cpufreq_governor(policy, CPUFREQ_GOV_START); - __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS); + if ((ret = __cpufreq_governor(policy, CPUFREQ_GOV_START)) || + (ret = __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS))) { + pr_err("%s: Failed to start governor\n", __func__); + return ret; + } } /* Don't touch sysfs links during light-weight init */ @@ -1172,7 +1180,7 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif, bool frozen) { unsigned int cpu = dev->id, cpus; - int new_cpu; + int new_cpu, ret; unsigned long flags; struct cpufreq_policy *policy; struct kobject *kobj; @@ -1196,8 +1204,13 @@ static int __cpufreq_remove_dev(struct device *dev, return -EINVAL; } - if (cpufreq_driver->target) - __cpufreq_governor(policy, CPUFREQ_GOV_STOP); + if (cpufreq_driver->target) { + ret = __cpufreq_governor(policy, CPUFREQ_GOV_STOP); + if (ret) { + pr_err("%s: Failed to stop governor\n", __func__); + return ret; + } + } #ifdef CONFIG_HOTPLUG_CPU if (!cpufreq_driver->setpolicy) @@ -1231,8 +1244,15 @@ static int __cpufreq_remove_dev(struct device *dev, /* If cpu is last user of policy, free policy */ if (cpus == 1) { - if (cpufreq_driver->target) - __cpufreq_governor(policy, CPUFREQ_GOV_POLICY_EXIT); + if (cpufreq_driver->target) { + ret = __cpufreq_governor(policy, + CPUFREQ_GOV_POLICY_EXIT); + if (ret) { + pr_err("%s: Failed to exit governor\n", + __func__); + return ret; + } + } if (!frozen) { lock_policy_rwsem_read(cpu); @@ -1263,8 +1283,12 @@ static int __cpufreq_remove_dev(struct device *dev, cpufreq_policy_free(policy); } else { if (cpufreq_driver->target) { - __cpufreq_governor(policy, CPUFREQ_GOV_START); - __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS); + if ((ret = __cpufreq_governor(policy, CPUFREQ_GOV_START)) || + (ret = __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS))) { + pr_err("%s: Failed to start governor\n", + __func__); + return ret; + } } } @@ -1912,7 +1936,7 @@ static int __cpufreq_set_policy(struct cpufreq_policy *policy, /* might be a policy change, too, so fall through */ } pr_debug("governor: change or update limits\n"); - __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS); + ret = __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS); } error_out: -- 2.7.4