Re: [PATCH] clk: implement clk_to_clk_hw using container_of_safe

[Sascha Hauer <sha@pengutronix.de>]

On Mon, Apr 24, 2023 at 02:02:11PM +0200, Ahmad Fatoum wrote:
> We basically opencode container_of_safe. The kernel implementation of
> container_of has also got a better diagnostic for mismatched arguments,
> so let's import it and use it.
> 
> Signed-off-by: Ahmad Fatoum <ahmad@a3f.at>
> ---
>  include/linux/clk.h          |  3 ++-
>  include/linux/container_of.h | 40 ++++++++++++++++++++++++++++++++++++
>  include/linux/kernel.h       | 12 +----------
>  3 files changed, 43 insertions(+), 12 deletions(-)
>  create mode 100644 include/linux/container_of.h
> 

Applied, thanks

Sascha

> diff --git a/include/linux/clk.h b/include/linux/clk.h
> index 29c697a00bd9..c78132d40582 100644
> --- a/include/linux/clk.h
> +++ b/include/linux/clk.h
> @@ -13,6 +13,7 @@
>  #include <linux/err.h>
>  #include <linux/spinlock.h>
>  #include <linux/stringify.h>
> +#include <linux/container_of.h>
>  #include <xfuncs.h>
>  
>  struct device;
> @@ -296,7 +297,7 @@ static inline struct clk *clk_hw_to_clk(const struct clk_hw *hw)
>  
>  static inline struct clk_hw *clk_to_clk_hw(const struct clk *clk)
>  {
> -	return IS_ERR(clk) ? ERR_CAST(clk) : (struct clk_hw *)container_of(clk, struct clk_hw, clk);
> +	return container_of_safe(clk, struct clk_hw, clk);
>  }
>  
>  struct clk_div_table {
> diff --git a/include/linux/container_of.h b/include/linux/container_of.h
> new file mode 100644
> index 000000000000..2f4944b791b8
> --- /dev/null
> +++ b/include/linux/container_of.h
> @@ -0,0 +1,40 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _LINUX_CONTAINER_OF_H
> +#define _LINUX_CONTAINER_OF_H
> +
> +#include <linux/build_bug.h>
> +#include <linux/err.h>
> +
> +#define typeof_member(T, m)	typeof(((T*)0)->m)
> +
> +/**
> + * container_of - cast a member of a structure out to the containing structure
> + * @ptr:	the pointer to the member.
> + * @type:	the type of the container struct this is embedded in.
> + * @member:	the name of the member within the struct.
> + *
> + */
> +#define container_of(ptr, type, member) ({				\
> +	void *__mptr = (void *)(ptr);					\
> +	static_assert(__same_type(*(ptr), ((type *)0)->member) ||	\
> +		      __same_type(*(ptr), void),			\
> +		      "pointer type mismatch in container_of()");	\
> +	((type *)(__mptr - offsetof(type, member))); })
> +
> +/**
> + * container_of_safe - cast a member of a structure out to the containing structure
> + * @ptr:	the pointer to the member.
> + * @type:	the type of the container struct this is embedded in.
> + * @member:	the name of the member within the struct.
> + *
> + * If IS_ERR_OR_NULL(ptr), ptr is returned unchanged.
> + */
> +#define container_of_safe(ptr, type, member) ({				\
> +	void *__mptr = (void *)(ptr);					\
> +	static_assert(__same_type(*(ptr), ((type *)0)->member) ||	\
> +		      __same_type(*(ptr), void),			\
> +		      "pointer type mismatch in container_of_safe()");	\
> +	IS_ERR_OR_NULL(__mptr) ? ERR_CAST(__mptr) :			\
> +		((type *)(__mptr - offsetof(type, member))); })
> +
> +#endif	/* _LINUX_CONTAINER_OF_H */
> diff --git a/include/linux/kernel.h b/include/linux/kernel.h
> index 44fc02df0bf9..0eb7bd21fe93 100644
> --- a/include/linux/kernel.h
> +++ b/include/linux/kernel.h
> @@ -7,6 +7,7 @@
>  #include <linux/barebox-wrapper.h>
>  #include <linux/limits.h>
>  #include <linux/math64.h>
> +#include <linux/container_of.h>
>  
>  #define ALIGN(x, a)		__ALIGN_MASK(x, (typeof(x))(a) - 1)
>  #define ALIGN_DOWN(x, a)	ALIGN((x) - ((a) - 1), (a))
> @@ -256,17 +257,6 @@ extern int hex_to_bin(char ch);
>  extern int __must_check hex2bin(u8 *dst, const char *src, size_t count);
>  extern char *bin2hex(char *dst, const void *src, size_t count);
>  
> -/**
> - * container_of - cast a member of a structure out to the containing structure
> - * @ptr:	the pointer to the member.
> - * @type:	the type of the container struct this is embedded in.
> - * @member:	the name of the member within the struct.
> - *
> - */
> -#define container_of(ptr, type, member) ({			\
> -	const typeof( ((type *)0)->member ) *__mptr = (ptr);	\
> -	(type *)( (char *)__mptr - offsetof(type,member) );})
> -
>  /*
>   * swap - swap value of @a and @b
>   */
> -- 
> 2.38.4
> 
> 
> 

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