From 8101f99703048ceaa31c756abe1098d099249ad9 Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Wed, 8 Jul 2015 15:12:15 +0530 Subject: cpufreq: cpufreq_add_dev: name goto labels based on what they do These labels are are named in two ways normally: - Based on what caused to jump to such labels - Based on what we do under such labels We follow the first naming convention today and that leads to multiple labels for doing the same work. Fix it by switching to the second way of naming them. Signed-off-by: Viresh Kumar Signed-off-by: Rafael J. Wysocki --- drivers/cpufreq/cpufreq.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) (limited to 'drivers/cpufreq/cpufreq.c') diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 26063afb3eba..702777b1d645 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1288,7 +1288,7 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif) recover_policy = false; policy = cpufreq_policy_alloc(dev); if (!policy) - goto nomem_out; + goto out_release_rwsem; } cpumask_copy(policy->cpus, cpumask_of(cpu)); @@ -1299,7 +1299,7 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif) ret = cpufreq_driver->init(policy); if (ret) { pr_debug("initialization failed\n"); - goto err_set_policy_cpu; + goto out_free_policy; } down_write(&policy->rwsem); @@ -1327,7 +1327,7 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif) policy->cur = cpufreq_driver->get(policy->cpu); if (!policy->cur) { pr_err("%s: ->get() failed\n", __func__); - goto err_get_freq; + goto out_exit_policy; } } @@ -1377,7 +1377,7 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif) if (!recover_policy) { ret = cpufreq_add_dev_interface(policy, dev); if (ret) - goto err_out_unregister; + goto out_exit_policy; blocking_notifier_call_chain(&cpufreq_policy_notifier_list, CPUFREQ_CREATE_POLICY, policy); @@ -1406,15 +1406,14 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif) return 0; -err_out_unregister: -err_get_freq: +out_exit_policy: up_write(&policy->rwsem); if (cpufreq_driver->exit) cpufreq_driver->exit(policy); -err_set_policy_cpu: +out_free_policy: cpufreq_policy_free(policy, recover_policy); -nomem_out: +out_release_rwsem: up_read(&cpufreq_rwsem); return ret; -- cgit v1.2.3 From 7f0fa40f5a587c2a026de776cc6a26373ac0f244 Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Wed, 8 Jul 2015 15:12:16 +0530 Subject: cpufreq: Properly handle errors from cpufreq_init_policy() cpufreq_init_policy() can fail, and we don't do anything except a call to ->exit() on that. The policy should be freed if this happens. Do it properly. Reported-and-tested-by: "Jon Medhurst (Tixy)" Signed-off-by: Viresh Kumar Signed-off-by: Rafael J. Wysocki --- drivers/cpufreq/cpufreq.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) (limited to 'drivers/cpufreq/cpufreq.c') diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 702777b1d645..a7b6ac6e048e 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1060,11 +1060,10 @@ static int cpufreq_add_dev_interface(struct cpufreq_policy *policy, return cpufreq_add_dev_symlink(policy); } -static void cpufreq_init_policy(struct cpufreq_policy *policy) +static int cpufreq_init_policy(struct cpufreq_policy *policy) { struct cpufreq_governor *gov = NULL; struct cpufreq_policy new_policy; - int ret = 0; memcpy(&new_policy, policy, sizeof(*policy)); @@ -1083,12 +1082,7 @@ static void cpufreq_init_policy(struct cpufreq_policy *policy) cpufreq_parse_governor(gov->name, &new_policy.policy, NULL); /* set default policy */ - ret = cpufreq_set_policy(policy, &new_policy); - if (ret) { - pr_debug("setting policy failed\n"); - if (cpufreq_driver->exit) - cpufreq_driver->exit(policy); - } + return cpufreq_set_policy(policy, &new_policy); } static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, @@ -1386,7 +1380,12 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif) write_unlock_irqrestore(&cpufreq_driver_lock, flags); } - cpufreq_init_policy(policy); + ret = cpufreq_init_policy(policy); + if (ret) { + pr_err("%s: Failed to initialize policy for cpu: %d (%d)\n", + __func__, cpu, ret); + goto out_remove_policy_notify; + } if (!recover_policy) { policy->user_policy.policy = policy->policy; @@ -1406,6 +1405,9 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif) return 0; +out_remove_policy_notify: + /* cpufreq_policy_free() will notify based on this */ + recover_policy = true; out_exit_policy: up_write(&policy->rwsem); -- cgit v1.2.3 From 4bc384ae6299d3f3a948efabda2a423e2a293ee0 Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Sat, 18 Jul 2015 11:31:03 +0530 Subject: cpufreq: propagate errors returned from __cpufreq_governor() Return codes aren't honored properly in cpufreq_set_policy(). This can lead to two problems: - wrong errors propagated to sysfs - we try to do next state-change even if the previous one failed cpufreq_governor_dbs() now returns proper errors on all invalid state-transition requests and this code should honor that. Reviewed-and-tested-by: Preeti U Murthy Signed-off-by: Viresh Kumar Signed-off-by: Rafael J. Wysocki --- drivers/cpufreq/cpufreq.c | 31 ++++++++++++++++++++++++------- 1 file changed, 24 insertions(+), 7 deletions(-) (limited to 'drivers/cpufreq/cpufreq.c') diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index a7b6ac6e048e..a3e8fb61cbcc 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -2295,16 +2295,31 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy, old_gov = policy->governor; /* end old governor */ if (old_gov) { - __cpufreq_governor(policy, CPUFREQ_GOV_STOP); + ret = __cpufreq_governor(policy, CPUFREQ_GOV_STOP); + if (ret) { + /* This can happen due to race with other operations */ + pr_debug("%s: Failed to Stop Governor: %s (%d)\n", + __func__, old_gov->name, ret); + return ret; + } + up_write(&policy->rwsem); - __cpufreq_governor(policy, CPUFREQ_GOV_POLICY_EXIT); + ret = __cpufreq_governor(policy, CPUFREQ_GOV_POLICY_EXIT); down_write(&policy->rwsem); + + if (ret) { + pr_err("%s: Failed to Exit Governor: %s (%d)\n", + __func__, old_gov->name, ret); + return ret; + } } /* start new governor */ policy->governor = new_policy->governor; - if (!__cpufreq_governor(policy, CPUFREQ_GOV_POLICY_INIT)) { - if (!__cpufreq_governor(policy, CPUFREQ_GOV_START)) + ret = __cpufreq_governor(policy, CPUFREQ_GOV_POLICY_INIT); + if (!ret) { + ret = __cpufreq_governor(policy, CPUFREQ_GOV_START); + if (!ret) goto out; up_write(&policy->rwsem); @@ -2316,11 +2331,13 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy, pr_debug("starting governor %s failed\n", policy->governor->name); if (old_gov) { policy->governor = old_gov; - __cpufreq_governor(policy, CPUFREQ_GOV_POLICY_INIT); - __cpufreq_governor(policy, CPUFREQ_GOV_START); + if (__cpufreq_governor(policy, CPUFREQ_GOV_POLICY_INIT)) + policy->governor = NULL; + else + __cpufreq_governor(policy, CPUFREQ_GOV_START); } - return -EINVAL; + return ret; out: pr_debug("governor: change or update limits\n"); -- cgit v1.2.3 From 454d3a2500a4eb33be85dde3bfba9e5f6b5efadc Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Wed, 22 Jul 2015 17:59:11 +0200 Subject: cpufreq: Remove cpufreq_rwsem cpufreq_rwsem was introduced in commit 6eed9404ab3c4 ("cpufreq: Use rwsem for protecting critical sections) in order to replace try_module_get() on the cpu-freq driver. That try_module_get() worked well until the refcount was so heavily used that module removal became more or less impossible. Though when looking at the various (undocumented) protection mechanisms in that code, the randomly sprinkeled around cpufreq_rwsem locking sites are superfluous. The policy, which is acquired in cpufreq_cpu_get() and released in cpufreq_cpu_put() is sufficiently protected already. cpufreq_cpu_get(cpu) /* Protects against concurrent driver removal */ read_lock_irqsave(&cpufreq_driver_lock, flags); policy = per_cpu(cpufreq_cpu_data, cpu); kobject_get(&policy->kobj); read_unlock_irqrestore(&cpufreq_driver_lock, flags); The reference on the policy serializes versus module unload already: cpufreq_unregister_driver() subsys_interface_unregister() __cpufreq_remove_dev_finish() per_cpu(cpufreq_cpu_data) = NULL; cpufreq_policy_put_kobj() If there is a reference held on the policy, i.e. obtained prior to the unregister call, then cpufreq_policy_put_kobj() will wait until that reference is dropped. So once subsys_interface_unregister() returns there is no policy pointer in flight and no new reference can be obtained. So that rwsem protection is useless. The other usage of cpufreq_rwsem in show()/store() of the sysfs interface is redundant as well because sysfs already does the proper kobject_get()/put() pairs. That leaves CPU hotplug versus module removal. The current down_write() around the write_lock() in cpufreq_unregister_driver() is silly at best as it protects actually nothing. The trivial solution to this is to prevent hotplug across cpufreq_unregister_driver completely. Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Rafael J. Wysocki --- drivers/cpufreq/cpufreq.c | 41 +++-------------------------------------- 1 file changed, 3 insertions(+), 38 deletions(-) (limited to 'drivers/cpufreq/cpufreq.c') diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index a3e8fb61cbcc..febda462681c 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -112,12 +112,6 @@ static inline bool has_target(void) return cpufreq_driver->target_index || cpufreq_driver->target; } -/* - * rwsem to guarantee that cpufreq driver module doesn't unload during critical - * sections - */ -static DECLARE_RWSEM(cpufreq_rwsem); - /* internal prototypes */ static int __cpufreq_governor(struct cpufreq_policy *policy, unsigned int event); @@ -277,10 +271,6 @@ EXPORT_SYMBOL_GPL(cpufreq_generic_get); * If corresponding call cpufreq_cpu_put() isn't made, the policy wouldn't be * freed as that depends on the kobj count. * - * It also takes a read-lock of 'cpufreq_rwsem' and doesn't put it back if a - * valid policy is found. This is done to make sure the driver doesn't get - * unregistered while the policy is being used. - * * Return: A valid policy on success, otherwise NULL on failure. */ struct cpufreq_policy *cpufreq_cpu_get(unsigned int cpu) @@ -291,9 +281,6 @@ struct cpufreq_policy *cpufreq_cpu_get(unsigned int cpu) if (WARN_ON(cpu >= nr_cpu_ids)) return NULL; - if (!down_read_trylock(&cpufreq_rwsem)) - return NULL; - /* get the cpufreq driver */ read_lock_irqsave(&cpufreq_driver_lock, flags); @@ -306,9 +293,6 @@ struct cpufreq_policy *cpufreq_cpu_get(unsigned int cpu) read_unlock_irqrestore(&cpufreq_driver_lock, flags); - if (!policy) - up_read(&cpufreq_rwsem); - return policy; } EXPORT_SYMBOL_GPL(cpufreq_cpu_get); @@ -320,13 +304,10 @@ EXPORT_SYMBOL_GPL(cpufreq_cpu_get); * * This decrements the kobject reference count incremented earlier by calling * cpufreq_cpu_get(). - * - * It also drops the read-lock of 'cpufreq_rwsem' taken at cpufreq_cpu_get(). */ void cpufreq_cpu_put(struct cpufreq_policy *policy) { kobject_put(&policy->kobj); - up_read(&cpufreq_rwsem); } EXPORT_SYMBOL_GPL(cpufreq_cpu_put); @@ -851,9 +832,6 @@ static ssize_t show(struct kobject *kobj, struct attribute *attr, char *buf) struct freq_attr *fattr = to_attr(attr); ssize_t ret; - if (!down_read_trylock(&cpufreq_rwsem)) - return -EINVAL; - down_read(&policy->rwsem); if (fattr->show) @@ -862,7 +840,6 @@ static ssize_t show(struct kobject *kobj, struct attribute *attr, char *buf) ret = -EIO; up_read(&policy->rwsem); - up_read(&cpufreq_rwsem); return ret; } @@ -879,9 +856,6 @@ static ssize_t store(struct kobject *kobj, struct attribute *attr, if (!cpu_online(policy->cpu)) goto unlock; - if (!down_read_trylock(&cpufreq_rwsem)) - goto unlock; - down_write(&policy->rwsem); /* Updating inactive policies is invalid, so avoid doing that. */ @@ -897,8 +871,6 @@ static ssize_t store(struct kobject *kobj, struct attribute *attr, unlock_policy_rwsem: up_write(&policy->rwsem); - - up_read(&cpufreq_rwsem); unlock: put_online_cpus(); @@ -1261,15 +1233,11 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif) if (cpu_is_offline(cpu)) return add_cpu_dev_symlink(per_cpu(cpufreq_cpu_data, cpu), cpu); - if (!down_read_trylock(&cpufreq_rwsem)) - return 0; - /* Check if this CPU already has a policy to manage it */ policy = per_cpu(cpufreq_cpu_data, cpu); if (policy && !policy_is_inactive(policy)) { WARN_ON(!cpumask_test_cpu(cpu, policy->related_cpus)); ret = cpufreq_add_policy_cpu(policy, cpu, dev); - up_read(&cpufreq_rwsem); return ret; } @@ -1395,8 +1363,6 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif) kobject_uevent(&policy->kobj, KOBJ_ADD); - up_read(&cpufreq_rwsem); - /* Callback for handling stuff after policy is ready */ if (cpufreq_driver->ready) cpufreq_driver->ready(policy); @@ -1416,8 +1382,6 @@ out_exit_policy: out_free_policy: cpufreq_policy_free(policy, recover_policy); out_release_rwsem: - up_read(&cpufreq_rwsem); - return ret; } @@ -2604,19 +2568,20 @@ int cpufreq_unregister_driver(struct cpufreq_driver *driver) pr_debug("unregistering driver %s\n", driver->name); + /* Protect against concurrent cpu hotplug */ + get_online_cpus(); subsys_interface_unregister(&cpufreq_interface); if (cpufreq_boost_supported()) cpufreq_sysfs_remove_file(&boost.attr); unregister_hotcpu_notifier(&cpufreq_cpu_notifier); - down_write(&cpufreq_rwsem); write_lock_irqsave(&cpufreq_driver_lock, flags); cpufreq_driver = NULL; write_unlock_irqrestore(&cpufreq_driver_lock, flags); - up_write(&cpufreq_rwsem); + put_online_cpus(); return 0; } -- cgit v1.2.3