Date:   Sat, 18 Mar 2023 18:14:50 +0100 (CET)
From:   Julia Lawall <julia.lawall@inria.fr>
To:     Sumitra Sharma <sumitraartsy@gmail.com>
cc:     Marc Dietrich <marvin24@gmx.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        ac100@lists.launchpad.net, linux-tegra@vger.kernel.org,
        linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org,
        outreachy@lists.linux.dev
Subject: Re: [PATCH] Staging: nvec: Change container_of macro to an inline
 function.
In-Reply-To: <20230318170514.GA49181@sumitra.com>
Message-ID: <alpine.DEB.2.22.394.2303181811260.2914@hadrien>
References: <20230318170514.GA49181@sumitra.com>
User-Agent: Alpine 2.22 (DEB 394 2020-01-19)
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On Sat, 18 Mar 2023, Sumitra Sharma wrote:

> The macro has the drawback that one cannot determine
> what type it applies to by looking at the definition.
> Hence this macro definition is not type-safe.
>
> The inline function gives the same benefits as the
> macro and only accepts the specific type of arguments.
> Use static because the definition only requires it to be
> visible in the current file.

Sumitra,

The subject line and log message could be a little less generic.  For the
subject line, one has the impression that you are changing the definition
of container_of itself.

The log message is also a bit wordy.  Something like the following would
be more concise and still present the issue:

Convert to_nvec_led from a macro to an inline function, to make the
relevant types apparent in the definition and to benefit from the type
checking performed by the compiler at call sites.

julia


>
> Signed-off-by: Sumitra Sharma <sumitraartsy@gmail.com>
> ---
>  drivers/staging/nvec/nvec_paz00.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/staging/nvec/nvec_paz00.c b/drivers/staging/nvec/nvec_paz00.c
> index 8b4da95081c8..9573ba762cdd 100644
> --- a/drivers/staging/nvec/nvec_paz00.c
> +++ b/drivers/staging/nvec/nvec_paz00.c
> @@ -14,8 +14,10 @@
>  #include <linux/platform_device.h>
>  #include "nvec.h"
>
> -#define to_nvec_led(led_cdev) \
> -	container_of(led_cdev, struct nvec_led, cdev)
> +static inline struct nvec_led *to_nvec_led(struct led_classdev *led_cdev)
> +{
> +	return container_of(led_cdev, struct nvec_led, cdev);
> +}
>
>  #define NVEC_LED_REQ {'\x0d', '\x10', '\x45', '\x10', '\x00'}
>
> --
> 2.25.1
>
>
>