On 19 November 2014 18:51, Tomeu Vizoso <tomeu.vizoso@xxxxxxxxxxxxx> wrote:
> Do it before it's assigned to cpufreq_cpu_data, otherwise we can get
> this warning when a driver tries to get the cpu frequency during
> initialization:
>
> ------------[ cut here ]------------
> WARNING: CPU: 1 PID: 64 at include/linux/kref.h:47 kobject_get+0x64/0x70()
> Modules linked in:
> CPU: 1 PID: 64 Comm: irq/77-tegra-ac Not tainted 3.18.0-rc4-next-20141114ccu-00050-g3eff942 #326
> [<c0016fac>] (unwind_backtrace) from [<c001272c>] (show_stack+0x10/0x14)
> [<c001272c>] (show_stack) from [<c06085d8>] (dump_stack+0x98/0xd8)
> [<c06085d8>] (dump_stack) from [<c002892c>] (warn_slowpath_common+0x84/0xb4)
> [<c002892c>] (warn_slowpath_common) from [<c00289f8>] (warn_slowpath_null+0x1c/0x24)
> [<c00289f8>] (warn_slowpath_null) from [<c0220290>] (kobject_get+0x64/0x70)
> [<c0220290>] (kobject_get) from [<c03e944c>] (cpufreq_cpu_get+0x88/0xc8)
> [<c03e944c>] (cpufreq_cpu_get) from [<c03e9500>] (cpufreq_get+0xc/0x64)
> [<c03e9500>] (cpufreq_get) from [<c0285288>] (actmon_thread_isr+0x134/0x198)
> [<c0285288>] (actmon_thread_isr) from [<c0069008>] (irq_thread_fn+0x1c/0x40)
> [<c0069008>] (irq_thread_fn) from [<c0069324>] (irq_thread+0x134/0x174)
> [<c0069324>] (irq_thread) from [<c0040290>] (kthread+0xdc/0xf4)
> [<c0040290>] (kthread) from [<c000f4b8>] (ret_from_fork+0x14/0x3c)
> ---[ end trace b7bd64a81b340c59 ]---
>
> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@xxxxxxxxxxxxx>
> ---
> drivers/cpufreq/cpufreq.c | 16 ++++++++++------
> 1 file changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 4473eba..954cb2f 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -898,12 +898,6 @@ static int cpufreq_add_dev_interface(struct cpufreq_policy *policy,
> struct freq_attr **drv_attr;
> int ret = 0;
>
> - /* prepare interface data */
> - ret = kobject_init_and_add(&policy->kobj, &ktype_cpufreq,
> - &dev->kobj, "cpufreq");
> - if (ret)
> - return ret;
> -
> /* set up files for this cpu device */
> drv_attr = cpufreq_driver->attr;
> while ((drv_attr) && (*drv_attr)) {
> @@ -1211,6 +1205,15 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
> }
>
> down_write(&policy->rwsem);
> +
> + /* prepare interface data */
> + ret = kobject_init_and_add(&policy->kobj, &ktype_cpufreq,
> + &dev->kobj, "cpufreq");
This should be done only when (!recover_policy) and so you can merge
it with the 'if' block just above down_write. Actually you can move down_write()
a little bit up as well, just after ->init()
> + if (ret) {
> + pr_err("%s: failed to init policy->kobj: %d\n", __func__, ret);
> + goto err_init_policy_kobj;
> + }
> +
> write_lock_irqsave(&cpufreq_driver_lock, flags);
> for_each_cpu(j, policy->cpus)
> per_cpu(cpufreq_cpu_data, j) = policy;
> @@ -1301,6 +1304,7 @@ err_get_freq:
> per_cpu(cpufreq_cpu_data, j) = NULL;
> write_unlock_irqrestore(&cpufreq_driver_lock, flags);
>
> +err_init_policy_kobj:
Oh, that's not enough and you need to get the relevant bits out from
the add_dev_interface() routine as well:
err_out_kobj_put:
kobject_put(&policy->kobj);
wait_for_completion(&policy->kobj_unregister);
> up_write(&policy->rwsem);
>
> if (cpufreq_driver->exit)
> --
> 1.9.3
>
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