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Date: Mon, 22 Jul 2013 15:41:45 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: Chanwoo Choi <cw00.choi@...sung.com>
Cc: rjw@...k.pl, linux-kernel@...r.kernel.org,
linux-pm@...r.kernel.org, cpufreq@...r.kernel.org,
kyungmin.park@...sung.com, myungjoo.ham@...sung.com,
Lists linaro-kernel <linaro-kernel@...ts.linaro.org>
Subject: Re: [PATCH 1/3 v6] cpufreq: Add debugfs directory for cpufreq
On 18 July 2013 16:47, Chanwoo Choi <cw00.choi@...sung.com> wrote:
> +#ifdef CONFIG_CPU_FREQ_STAT
> +/* The cpufreq_debugfs is used to create debugfs root directory for CPUFreq. */
> +static struct dentry *cpufreq_debugfs;
> +
> +static int cpufreq_create_debugfs_dir(struct cpufreq_policy *policy,
> + struct device *dev)
> +{
> + char name[CPUFREQ_NAME_LEN];
> + unsigned int cpus, size, idx;
> +
> + if (!cpufreq_debugfs)
> + return -EINVAL;
> +
> + cpus = cpumask_weight(policy->cpus);
I remember I told you not to use policy->cpus for this purpose?? But
related_cpus.
> + idx = cpus > 1 ? policy->cpu : 0;
> + policy->cpu_debugfs[idx] = debugfs_create_dir(name, cpufreq_debugfs);
This is broken. A policy may contain cpus 9,10 only.. You will allocate array
for 2 cpus and try to access cpu_debugfs[9] :)
> + if (!policy->cpu_debugfs[idx]) {
> + pr_err("creating debugfs directory failed\n");
> + return -ENODEV;
> + }
> +
> + return 0;
> +}
> +
> +static int cpufreq_create_debugfs_symlink(struct cpufreq_policy *policy,
> + unsigned int src_cpu,
> + unsigned int dest_cpu)
Only use policy and cpu for which symlink has to be created as param
to this routine. And create link to policy->cpu.
> +{
> + char symlink_name[CPUFREQ_NAME_LEN];
> + char target_name[CPUFREQ_NAME_LEN];
> +
> + if (!cpufreq_debugfs)
> + return -EINVAL;
> +
> + if (!policy->cpu_debugfs[src_cpu])
> + return -EINVAL;
> +
> + sprintf(symlink_name, "cpu%d", dest_cpu);
> + sprintf(target_name, "./cpu%d", src_cpu);
> + policy->cpu_debugfs[dest_cpu] = debugfs_create_symlink(
> + symlink_name,
> + cpufreq_debugfs,
> + target_name);
> + if (!policy->cpu_debugfs[dest_cpu]) {
> + pr_err("creating debugfs symlink failed\n");
> + return -ENODEV;
> + }
> +
> + return 0;
> +}
> +
> +static void cpufreq_remove_debugfs_dir(struct cpufreq_policy *policy,
> + unsigned int cpu)
> +{
> + unsigned int idx = cpumask_weight(policy->cpus) > 1 ? cpu : 0;
> +
> + if (!policy->cpu_debugfs[idx])
> + return;
> +
> + debugfs_remove_recursive(policy->cpu_debugfs[idx]);
Whey do we need recursive here? And what exactly does recursive will
do?
> +}
> +
same problem here too.
> +static void cpufreq_move_debugfs_dir(struct cpufreq_policy *policy,
> + unsigned int new_cpu)
> +{
> + struct dentry *old_entry, *new_entry;
> + char new_dir_name[CPUFREQ_NAME_LEN];
> + unsigned int j, old_cpu = policy->cpu;
> +
> + if (!policy->cpu_debugfs[new_cpu])
> + return;
> +
> + /*
> + * Remove symbolic link of debugfs directory except for debugfs
> + * directory of old_cpu.
> + */
> + for_each_present_cpu(j) {
> + if (old_cpu == j)
> + continue;
> +
> + debugfs_remove(policy->cpu_debugfs[j]);
Why you need this? We aren't removing the earlier dentry at all here.
> + }
> +
> + /*
> + * Change debugfs directory name from as following:
> + * - old debugfs dir name : /sys/kernel/debugfs/cpufreq/cpu${old_cpu}
> + * - new debugfs dir name : /sys/kernel/debugfs/cpufreq/cpu${new_cpu}
> + */
> + sprintf(new_dir_name, "cpu%d", new_cpu);
> + old_entry = policy->cpu_debugfs[old_cpu];
> + new_entry = debugfs_rename(cpufreq_debugfs, old_entry,
> + cpufreq_debugfs, new_dir_name);
This routine returns old_entry only.. and so you can simply create a
single routine with name dentry.
> + if (!new_entry) {
> + pr_err("changing debugfs directory name failed\n");
> + goto err_rename;
> + }
> +
> + policy->cpu_debugfs[new_cpu] = new_entry;
> + policy->cpu_debugfs[old_cpu] = NULL;
> +
> + /* Create again symbolic link of debugfs directory */
> + for_each_present_cpu(j) {
present_cpu?? We discussed this before.. You will break multi cluster
systems.
> + if (new_cpu == j)
> + continue;
> +
> + cpufreq_create_debugfs_symlink(policy, new_cpu, j);
> + }
> +
> + return;
> +
> +err_rename:
> + for_each_present_cpu(j) {
> + if (old_cpu == j)
> + continue;
> +
> + cpufreq_create_debugfs_symlink(policy, old_cpu, j);
> + }
> +}
> +
> +static int cpufreq_create_debugfs(void)
> +{
> + cpufreq_debugfs = debugfs_create_dir("cpufreq", NULL);
> + if (!cpufreq_debugfs) {
> + pr_err("creating debugfs root failed\n");
> + return -ENODEV;
> + }
> +
> + return 0;
> +}
> +
> +static void cpufreq_remove_debugfs(void)
> +{
> + if (cpufreq_debugfs)
> + debugfs_remove_recursive(cpufreq_debugfs);
> +}
> +#else
> +static int cpufreq_create_debugfs_dir(struct cpufreq_policy *policy,
> + struct device *dev) { return 0; }
> +static int cpufreq_create_debugfs_symlink(struct cpufreq_policy *policy,
> + unsigned int src_cpu,
> + unsigned int dest_cpu) { return 0;}
> +static void cpufreq_remove_debugfs_dir(struct cpufreq_policy *policy,
> + unsigned int cpu) { }
> +static void cpufreq_move_debugfs_dir(struct cpufreq_policy *policy,
> + unsigned int new_cpu) { }
> +static int cpufreq_create_debugfs(void) { return 0; }
> +static void cpufreq_remove_debugfs(void) { }
make all above #else part routines inline.
> +#endif
> +
> /* symlink affected CPUs */
> static int cpufreq_add_dev_symlink(unsigned int cpu,
> struct cpufreq_policy *policy)
> @@ -726,6 +885,8 @@ static int cpufreq_add_dev_symlink(unsigned int cpu,
> cpufreq_cpu_put(managed_policy);
> return ret;
> }
> +
> + cpufreq_create_debugfs_symlink(policy, cpu, j);
> }
> return ret;
> }
> @@ -777,6 +938,9 @@ static int cpufreq_add_dev_interface(unsigned int cpu,
> }
> write_unlock_irqrestore(&cpufreq_driver_lock, flags);
>
> + /* prepare interface data for debugfs */
> + cpufreq_create_debugfs_dir(policy, dev);
> +
> ret = cpufreq_add_dev_symlink(cpu, policy);
> if (ret)
> goto err_out_kobj_put;
> @@ -839,6 +1003,8 @@ static int cpufreq_add_policy_cpu(unsigned int cpu, unsigned int sibling,
> return ret;
> }
>
> + cpufreq_create_debugfs_symlink(policy, sibling, cpu);
> +
> return 0;
> }
> #endif
> @@ -1046,6 +1212,7 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif
>
> if (cpu != data->cpu) {
> sysfs_remove_link(&dev->kobj, "cpufreq");
> + cpufreq_remove_debugfs_dir(data, cpu);
> } else if (cpus > 1) {
> /* first sibling now owns the new sysfs dir */
> cpu_dev = get_cpu_device(cpumask_first(data->cpus));
> @@ -1068,6 +1235,8 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif
> return -EINVAL;
> }
>
> + cpufreq_move_debugfs_dir(data, cpu_dev->id);
> +
> WARN_ON(lock_policy_rwsem_write(cpu));
> update_policy_cpu(data, cpu_dev->id);
> unlock_policy_rwsem_write(cpu);
> @@ -1089,6 +1258,8 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif
> unlock_policy_rwsem_read(cpu);
> kobject_put(kobj);
>
> + cpufreq_remove_debugfs_dir(data, cpu);
> +
> /* we need to make sure that the underlying kobj is actually
> * not referenced anymore by anybody before we proceed with
> * unloading.
> @@ -1894,6 +2065,8 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
> cpufreq_driver = driver_data;
> write_unlock_irqrestore(&cpufreq_driver_lock, flags);
>
> + cpufreq_create_debugfs();
Why you moved this to register_driver? It was fine at cpufreq_core_init()
> ret = subsys_interface_register(&cpufreq_interface);
> if (ret)
> goto err_null_driver;
> @@ -1918,12 +2091,14 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
> }
>
> register_hotcpu_notifier(&cpufreq_cpu_notifier);
> +
unrelated change.
> pr_debug("driver %s up and running\n", driver_data->name);
>
> return 0;
> err_if_unreg:
> subsys_interface_unregister(&cpufreq_interface);
> err_null_driver:
> + cpufreq_remove_debugfs();
> write_lock_irqsave(&cpufreq_driver_lock, flags);
> cpufreq_driver = NULL;
> write_unlock_irqrestore(&cpufreq_driver_lock, flags);
> @@ -1949,6 +2124,8 @@ int cpufreq_unregister_driver(struct cpufreq_driver *driver)
>
> pr_debug("unregistering driver %s\n", driver->name);
>
> + cpufreq_remove_debugfs();
And so you don't need this.
> subsys_interface_unregister(&cpufreq_interface);
> unregister_hotcpu_notifier(&cpufreq_cpu_notifier);
>
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index 037d36a..825f379 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -115,6 +115,7 @@ struct cpufreq_policy {
>
> struct kobject kobj;
> struct completion kobj_unregister;
> + struct dentry **cpu_debugfs;
> };
>
> #define CPUFREQ_ADJUST (0)
> --
> 1.8.0
>
--
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