netdev - Re: [PATCH net-next 07/15] ice: add ICE_READ/WRITE_CGU_REG_OR

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Message-ID: <20250621082321.724b65dd@kernel.org>
Date: Sat, 21 Jun 2025 08:23:21 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Tony Nguyen <anthony.l.nguyen@...el.com>
Cc: davem@...emloft.net, pabeni@...hat.com, edumazet@...gle.com,
 andrew+netdev@...n.ch, netdev@...r.kernel.org, Karol Kolacinski
 <karol.kolacinski@...el.com>, jacob.e.keller@...el.com,
 przemyslaw.kitszel@...el.com, richardcochran@...il.com, Michal Kubiak
 <michal.kubiak@...el.com>, Milena Olech <milena.olech@...el.com>, Rinitha S
 <sx.rinitha@...el.com>
Subject: Re: [PATCH net-next 07/15] ice: add ICE_READ/WRITE_CGU_REG_OR_DIE
 helpers

On Wed, 18 Jun 2025 10:42:19 -0700 Tony Nguyen wrote:
> +#define ICE_READ_CGU_REG_OR_DIE(hw, addr, val)                     \
> +	do {                                                       \
> +		int __err = ice_read_cgu_reg((hw), (addr), (val)); \
> +								   \
> +		if (__err)                                         \
> +			return __err;                              \
> +	} while (0)
>  int ice_write_cgu_reg(struct ice_hw *hw, u32 addr, u32 val);
> +#define ICE_WRITE_CGU_REG_OR_DIE(hw, addr, val)                     \
> +	do {                                                        \
> +		int __err = ice_write_cgu_reg((hw), (addr), (val)); \
> +								    \
> +		if (__err)                                          \
> +			return __err;                               \
> +	} while (0)

Quoting documentation:

  12) Macros, Enums and RTL
  -------------------------
  
[...]

  Things to avoid when using macros:
  
  1) macros that affect control flow:
  
  .. code-block:: c
  
  	#define FOO(x)					\
  		do {					\
  			if (blah(x) < 0)		\
  				return -EBUGGERED;	\
  		} while (0)
  
  is a **very** bad idea.  It looks like a function call but exits the ``calling``
  function; don't break the internal parsers of those who will read the code.
  
See: https://www.kernel.org/doc/html/next/process/coding-style.html#macros-enums-and-rtl