linux-kernel - Re: [PATCH v2 2/2] vsprintf: remove redundant and unused %pCn format specifier

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Message-ID: <aa840586-cd70-417f-82c2-bb887f337720@linux.dev>
Date: Tue, 11 Mar 2025 17:34:58 +0800
From: Yanteng Si <si.yanteng@...ux.dev>
To: Luca Ceresoli <luca.ceresoli@...tlin.com>,
 "Rafael J. Wysocki" <rafael@...nel.org>,
 Daniel Lezcano <daniel.lezcano@...aro.org>, Zhang Rui <rui.zhang@...el.com>,
 Lukasz Luba <lukasz.luba@....com>,
 Florian Fainelli <florian.fainelli@...adcom.com>, Ray Jui
 <rjui@...adcom.com>, Scott Branden <sbranden@...adcom.com>,
 Broadcom internal kernel review list
 <bcm-kernel-feedback-list@...adcom.com>, Petr Mladek <pmladek@...e.com>,
 Steven Rostedt <rostedt@...dmis.org>,
 Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
 Rasmus Villemoes <linux@...musvillemoes.dk>,
 Sergey Senozhatsky <senozhatsky@...omium.org>,
 Jonathan Corbet <corbet@....net>, Andrew Morton <akpm@...ux-foundation.org>,
 Alex Shi <alexs@...nel.org>
Cc: Binbin Zhou <zhoubinbin@...ngson.cn>,
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
 Michael Turquette <mturquette@...libre.com>, Stephen Boyd
 <sboyd@...nel.org>, Geert Uytterhoeven <geert+renesas@...der.be>,
 Liu Ying <victor.liu@....com>, linux-clk@...r.kernel.org,
 linux-pm@...r.kernel.org, linux-rpi-kernel@...ts.infradead.org,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
 linux-doc@...r.kernel.org
Subject: Re: [PATCH v2 2/2] vsprintf: remove redundant and unused %pCn format
 specifier


在 3/11/25 5:21 PM, Luca Ceresoli 写道:
> %pC and %pCn print the same string, and commit 900cca294425 ("lib/vsprintf:
> add %pC{,n,r} format specifiers for clocks") introducing them does not
> clarify any intended difference. It can be assumed %pC is a default for
> %pCn as some other specifiers do, but not all are consistent with this
> policy. Moreover there is now no other suffix other than 'n', which makes a
> default not really useful.
>
> All users in the kernel were using %pC except for one which has been
> converted. So now remove %pCn and all the unnecessary extra code and
> documentation.
>
> Acked-by: Stephen Boyd <sboyd@...nel.org>
> Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>
> Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>

Reviewed-by: Yanteng Si <si.yanteng@...ux.dev>


Thanks,

Yanteng

>
> ---
>
> Changes in v2:
> - update Chinese documentation (change acked by Yanteng Si <si.yanteng@...ux.dev>)
> ---
>   Documentation/core-api/printk-formats.rst                    |  3 +--
>   Documentation/translations/zh_CN/core-api/printk-formats.rst |  3 +--
>   lib/vsprintf.c                                               | 10 ++--------
>   3 files changed, 4 insertions(+), 12 deletions(-)
>
> diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst
> index ecccc0473da9c10f45f2464566f690472c61401e..f3009e6ec80a864c330c8812efcd82c12f4066b3 100644
> --- a/Documentation/core-api/printk-formats.rst
> +++ b/Documentation/core-api/printk-formats.rst
> @@ -571,9 +571,8 @@ struct clk
>   ::
>   
>   	%pC	pll1
> -	%pCn	pll1
>   
> -For printing struct clk structures. %pC and %pCn print the name of the clock
> +For printing struct clk structures. %pC prints the name of the clock
>   (Common Clock Framework) or a unique 32-bit ID (legacy clock framework).
>   
>   Passed by reference.
> diff --git a/Documentation/translations/zh_CN/core-api/printk-formats.rst b/Documentation/translations/zh_CN/core-api/printk-formats.rst
> index bd36d35eba4eb124be43a66227059a30429e4135..96a917ecc93f2a4872784b6d8e3f98bcb9f5f737 100644
> --- a/Documentation/translations/zh_CN/core-api/printk-formats.rst
> +++ b/Documentation/translations/zh_CN/core-api/printk-formats.rst
> @@ -523,9 +523,8 @@ clk结构体
>   ::
>   
>   	%pC	pll1
> -	%pCn	pll1
>   
> -用于打印clk结构。%pC 和 %pCn 打印时钟的名称（通用时钟框架）或唯一的32位
> +用于打印clk结构。%pC 打印时钟的名称（通用时钟框架）或唯一的32位
>   ID（传统时钟框架）。
>   
>   通过引用传递。
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> index 56fe96319292674c9f79559cf78dd0d99d1a1f06..143d55cb1c12acac21a6c6bafd255437e878f280 100644
> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> @@ -1969,15 +1969,11 @@ char *clock(char *buf, char *end, struct clk *clk, struct printf_spec spec,
>   	if (check_pointer(&buf, end, clk, spec))
>   		return buf;
>   
> -	switch (fmt[1]) {
> -	case 'n':
> -	default:
>   #ifdef CONFIG_COMMON_CLK
> -		return string(buf, end, __clk_get_name(clk), spec);
> +	return string(buf, end, __clk_get_name(clk), spec);
>   #else
> -		return ptr_to_id(buf, end, clk, spec);
> +	return ptr_to_id(buf, end, clk, spec);
>   #endif
> -	}
>   }
>   
>   static
> @@ -2382,8 +2378,6 @@ char *rust_fmt_argument(char *buf, char *end, void *ptr);
>    *      T    time64_t
>    * - 'C' For a clock, it prints the name (Common Clock Framework) or address
>    *       (legacy clock framework) of the clock
> - * - 'Cn' For a clock, it prints the name (Common Clock Framework) or address
> - *        (legacy clock framework) of the clock
>    * - 'G' For flags to be printed as a collection of symbolic strings that would
>    *       construct the specific value. Supported flags given by option:
>    *       p page flags (see struct page) given as pointer to unsigned long
>