On Wed, Apr 11, 2012 at 06:02:50PM -0700, Mike Turquette wrote:
> This patch cleans up clk_register and solves a few bugs by teaching
> clk_register and __clk_init to return error codes (instead of just NULL)
> to better align with the existing clk.h api.
> 
> Along with that change this patch also introduces a new behavior whereby
> clk_register copies the parent_names array, thus allowing platforms to
> declare their parent_names arrays as __initdata.
> 
> Signed-off-by: Mike Turquette <mturque...@linaro.org>
> Cc: Arnd Bergman <arnd.bergm...@linaro.org>
> Cc: Olof Johansson <o...@lixom.net>
> Cc: Russell King <li...@arm.linux.org.uk>
> Cc: Sascha Hauer <s.ha...@pengutronix.de>
> Cc: Shawn Guo <shawn....@freescale.com>
> Cc: Richard Zhao <richard.z...@linaro.org>
> Cc: Saravana Kannan <skan...@codeaurora.org>
> Cc: Mark Brown <broo...@opensource.wolfsonmicro.com>
> Cc: Andrew Lunn <and...@lunn.ch>
> Cc: Rajendra Nayak <rna...@ti.com>
> Cc: Viresh Kumar <viresh.ku...@st.com>
> ---
>  drivers/clk/clk.c            |   61 +++++++++++++++++++++++++++++++++--------
>  include/linux/clk-private.h  |    4 ++-
>  include/linux/clk-provider.h |    3 +-
>  3 files changed, 54 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index ddade87..af2bf12 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -1185,34 +1185,41 @@ EXPORT_SYMBOL_GPL(clk_set_parent);
>   * very large numbers of clocks that need to be statically initialized.  It 
> is
>   * a layering violation to include clk-private.h from any code which 
> implements
>   * a clock's .ops; as such any statically initialized clock data MUST be in a
> - * separate C file from the logic that implements it's operations.
> + * separate C file from the logic that implements it's operations.  Returns 0
> + * on success, otherwise an error code.
>   */
> -void __clk_init(struct device *dev, struct clk *clk)
> +int __clk_init(struct device *dev, struct clk *clk)
>  {
> -     int i;
> +     int i, ret = 0;
>       struct clk *orphan;
>       struct hlist_node *tmp, *tmp2;
>  
>       if (!clk)
> -             return;
> +             return -EINVAL;
>  
>       mutex_lock(&prepare_lock);
>  
>       /* check to see if a clock with this name is already registered */
> -     if (__clk_lookup(clk->name))
> +     if (__clk_lookup(clk->name)) {
> +             pr_debug("%s: clk %s already initialized\n",
> +                             __func__, clk->name);
> +             ret = -EEXIST;
>               goto out;
> +     }
>  
>       /* check that clk_ops are sane.  See Documentation/clk.txt */
>       if (clk->ops->set_rate &&
>                       !(clk->ops->round_rate && clk->ops->recalc_rate)) {
>               pr_warning("%s: %s must implement .round_rate & .recalc_rate\n",
>                               __func__, clk->name);
> +             ret = -EINVAL;
>               goto out;
>       }
>  
>       if (clk->ops->set_parent && !clk->ops->get_parent) {
>               pr_warning("%s: %s must implement .get_parent & .set_parent\n",
>                               __func__, clk->name);
> +             ret = -EINVAL;
>               goto out;
>       }
>  
> @@ -1308,7 +1315,7 @@ void __clk_init(struct device *dev, struct clk *clk)
>  out:
>       mutex_unlock(&prepare_lock);
>  
> -     return;
> +     return ret;
>  }
>  
>  /**
> @@ -1324,29 +1331,59 @@ out:
>   * clk_register is the primary interface for populating the clock tree with 
> new
>   * clock nodes.  It returns a pointer to the newly allocated struct clk which
>   * cannot be dereferenced by driver code but may be used in conjuction with 
> the
> - * rest of the clock API.
> + * rest of the clock API.  In the event of an error clk_register will return 
> an
> + * error code; drivers must test for an error code after calling 
> clk_register.
>   */
>  struct clk *clk_register(struct device *dev, const char *name,
>               const struct clk_ops *ops, struct clk_hw *hw,
>               const char **parent_names, u8 num_parents, unsigned long flags)
>  {
> +     int i, ret = -ENOMEM;

I suggest to move the initialization of ret from here...

>       struct clk *clk;
>  
>       clk = kzalloc(sizeof(*clk), GFP_KERNEL);
> -     if (!clk)
> -             return NULL;
> +     if (!clk) {
> +             pr_err("%s: could not allocate clk\n", __func__);
> +             goto fail_out;
> +     }
>  
>       clk->name = name;
>       clk->ops = ops;
>       clk->hw = hw;
>       clk->flags = flags;
> -     clk->parent_names = parent_names;
>       clk->num_parents = num_parents;
>       hw->clk = clk;
>  
> -     __clk_init(dev, clk);
> +     /* allocate local copy in case parent_names is __initdata */
> +     clk->parent_names = kzalloc((sizeof(char*) * num_parents),
> +                     GFP_KERNEL);
> +
> +     if (!clk->parent_names) {
> +             pr_err("%s: could not allocate clk->parent_names\n", __func__);
> +             goto fail_parent_names;
> +     }
> +
> +     /* copy each string name in case parent_names is __initdata */

... to here.

The rationale is that when this code is changed later someone might use
ret above and doesn't remember that the code below expects ret to be
initialized with -ENOMEM. Also it's easier to see that the code is
correct.

Sascha

> +     for (i = 0; i < num_parents; i++) {
> +             clk->parent_names[i] = kstrdup(parent_names[i], GFP_KERNEL);
> +             if (!clk->parent_names[i]) {
> +                     pr_err("%s: could not copy parent_names\n", __func__);
> +                     goto fail_parent_names_copy;
> +             }
> +     }
> +
> +     ret = __clk_init(dev, clk);
> +     if (!ret)
> +             return clk;
>  
> -     return clk;
> +fail_parent_names_copy:
> +     while (--i >= 0)
> +             kfree(clk->parent_names[i]);
> +     kfree(clk->parent_names);
> +fail_parent_names:
> +     kfree(clk);
> +fail_out:
> +     return ERR_PTR(ret);
>  }
>  EXPORT_SYMBOL_GPL(clk_register);
>  
> diff --git a/include/linux/clk-private.h b/include/linux/clk-private.h
> index e9c8b98..e7032fd 100644
> --- a/include/linux/clk-private.h
> +++ b/include/linux/clk-private.h
> @@ -181,8 +181,10 @@ struct clk {
>   *
>   * It is not necessary to call clk_register if __clk_init is used directly 
> with
>   * statically initialized clock data.
> + *
> + * Returns 0 on success, otherwise an error code.
>   */
> -void __clk_init(struct device *dev, struct clk *clk);
> +int __clk_init(struct device *dev, struct clk *clk);
>  
>  #endif /* CONFIG_COMMON_CLK */
>  #endif /* CLK_PRIVATE_H */
> diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
> index 8981435..97f9fab 100644
> --- a/include/linux/clk-provider.h
> +++ b/include/linux/clk-provider.h
> @@ -274,7 +274,8 @@ struct clk *clk_register_mux(struct device *dev, const 
> char *name,
>   * clk_register is the primary interface for populating the clock tree with 
> new
>   * clock nodes.  It returns a pointer to the newly allocated struct clk which
>   * cannot be dereferenced by driver code but may be used in conjuction with 
> the
> - * rest of the clock API.
> + * rest of the clock API.  In the event of an error clk_register will return 
> an
> + * error code; drivers must test for an error code after calling 
> clk_register.
>   */
>  struct clk *clk_register(struct device *dev, const char *name,
>               const struct clk_ops *ops, struct clk_hw *hw,
> -- 
> 1.7.5.4
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-ker...@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 

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