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

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Message-Id: <20250307-vsprintf-pcn-v1-2-df0b2ccf610f@bootlin.com>
Date: Fri, 07 Mar 2025 12:19:08 +0100
From: Luca Ceresoli <luca.ceresoli@...tlin.com>
To: "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>
Cc: 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, 
 Luca Ceresoli <luca.ceresoli@...tlin.com>
Subject: [PATCH 2/2] vsprintf: remove redundant and unused %pCn format
 specifier

%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.

Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>
---
 Documentation/core-api/printk-formats.rst |  3 +--
 lib/vsprintf.c                            | 10 ++--------
 2 files changed, 3 insertions(+), 10 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/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

-- 
2.48.1