linux-kernel - Re: [PATCH 1/4] PM / OPP: add some lockdep annotations

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Message-ID: <CAKohponveD5W3=L5rd_vVjs2CTHcH93qS8S3H-Bg-S-DckiViA@mail.gmail.com>
Date:	Wed, 17 Dec 2014 09:40:42 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Dmitry Torokhov <dtor@...omium.org>
Cc:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Stefan Wahren <stefan.wahren@...e.com>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	Nishanth Menon <nm@...com>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/4] PM / OPP: add some lockdep annotations

On 17 December 2014 at 04:39, Dmitry Torokhov <dtor@...omium.org> wrote:
> Certain OPP APIs need to be called under RCU lock; let's add a few
> rcu_lockdep_assert() calls to warn about potential misuse.
>
> Signed-off-by: Dmitry Torokhov <dtor@...omium.org>
> ---
>  drivers/base/power/opp.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
> index d24dd614a..b78c14d 100644
> --- a/drivers/base/power/opp.c
> +++ b/drivers/base/power/opp.c
> @@ -108,6 +108,14 @@ static LIST_HEAD(dev_opp_list);
>  /* Lock to allow exclusive modification to the device and opp lists */
>  static DEFINE_MUTEX(dev_opp_list_lock);
>
> +#define opp_rcu_lockdep_assert()                                       \
> +do {                                                                   \
> +       rcu_lockdep_assert(rcu_read_lock_held() ||                      \
> +                               lockdep_is_held(&dev_opp_list_lock),    \
> +                          "Missing rcu_read_lock() or "                \
> +                          "dev_opp_list_lock protection");             \
> +} while (0)
> +
>  /**
>   * find_device_opp() - find device_opp struct using device pointer
>   * @dev:       device pointer used to lookup device OPPs
> @@ -218,6 +226,8 @@ int dev_pm_opp_get_opp_count(struct device *dev)
>         struct dev_pm_opp *temp_opp;
>         int count = 0;
>
> +       opp_rcu_lockdep_assert();
> +
>         dev_opp = find_device_opp(dev);
>         if (IS_ERR(dev_opp)) {
>                 int r = PTR_ERR(dev_opp);
> @@ -267,6 +277,8 @@ struct dev_pm_opp *dev_pm_opp_find_freq_exact(struct device *dev,
>         struct device_opp *dev_opp;
>         struct dev_pm_opp *temp_opp, *opp = ERR_PTR(-ERANGE);
>
> +       opp_rcu_lockdep_assert();
> +
>         dev_opp = find_device_opp(dev);
>         if (IS_ERR(dev_opp)) {
>                 int r = PTR_ERR(dev_opp);
> @@ -313,6 +325,8 @@ struct dev_pm_opp *dev_pm_opp_find_freq_ceil(struct device *dev,
>         struct device_opp *dev_opp;
>         struct dev_pm_opp *temp_opp, *opp = ERR_PTR(-ERANGE);
>
> +       opp_rcu_lockdep_assert();
> +
>         if (!dev || !freq) {
>                 dev_err(dev, "%s: Invalid argument freq=%p\n", __func__, freq);
>                 return ERR_PTR(-EINVAL);
> @@ -361,6 +375,8 @@ struct dev_pm_opp *dev_pm_opp_find_freq_floor(struct device *dev,
>         struct device_opp *dev_opp;
>         struct dev_pm_opp *temp_opp, *opp = ERR_PTR(-ERANGE);
>
> +       opp_rcu_lockdep_assert();
> +
>         if (!dev || !freq) {
>                 dev_err(dev, "%s: Invalid argument freq=%p\n", __func__, freq);
>                 return ERR_PTR(-EINVAL);

Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
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