linux-kernel - [PATCH 4.9 016/101] lib/vsprintf: Remove atomic-unsafe support for %pCr

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Message-Id: <20180701160757.782482744@linuxfoundation.org>
Date:   Sun,  1 Jul 2018 18:21:02 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org, Jia-Ju Bai <baijiaju1990@...il.com>,
        Jonathan Corbet <corbet@....net>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Eduardo Valentin <edubezval@...il.com>,
        Eric Anholt <eric@...olt.net>,
        Stefan Wahren <stefan.wahren@...e.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Petr Mladek <pmladek@...e.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        linux-doc@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-serial@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-renesas-soc@...r.kernel.org,
        Geert Uytterhoeven <geert+renesas@...der.be>
Subject: [PATCH 4.9 016/101] lib/vsprintf: Remove atomic-unsafe support for %pCr

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Geert Uytterhoeven <geert+renesas@...der.be>

commit 666902e42fd8344b923c02dc5b0f37948ff4f225 upstream.

"%pCr" formats the current rate of a clock, and calls clk_get_rate().
The latter obtains a mutex, hence it must not be called from atomic
context.

Remove support for this rarely-used format, as vsprintf() (and e.g.
printk()) must be callable from any context.

Any remaining out-of-tree users will start seeing the clock's name
printed instead of its rate.

Reported-by: Jia-Ju Bai <baijiaju1990@...il.com>
Fixes: 900cca2944254edd ("lib/vsprintf: add %pC{,n,r} format specifiers for clocks")
Link: http://lkml.kernel.org/r/1527845302-12159-5-git-send-email-geert+renesas@glider.be
To: Jia-Ju Bai <baijiaju1990@...il.com>
To: Jonathan Corbet <corbet@....net>
To: Michael Turquette <mturquette@...libre.com>
To: Stephen Boyd <sboyd@...nel.org>
To: Zhang Rui <rui.zhang@...el.com>
To: Eduardo Valentin <edubezval@...il.com>
To: Eric Anholt <eric@...olt.net>
To: Stefan Wahren <stefan.wahren@...e.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc: Petr Mladek <pmladek@...e.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: linux-doc@...r.kernel.org
Cc: linux-clk@...r.kernel.org
Cc: linux-pm@...r.kernel.org
Cc: linux-serial@...r.kernel.org
Cc: linux-arm-kernel@...ts.infradead.org
Cc: linux-renesas-soc@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Cc: Geert Uytterhoeven <geert+renesas@...der.be>
Cc: stable@...r.kernel.org # 4.1+
Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
Signed-off-by: Petr Mladek <pmladek@...e.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 Documentation/printk-formats.txt |    3 +--
 lib/vsprintf.c                   |    3 ---
 2 files changed, 1 insertion(+), 5 deletions(-)

--- a/Documentation/printk-formats.txt
+++ b/Documentation/printk-formats.txt
@@ -279,11 +279,10 @@ struct clk:
 
 	%pC	pll1
 	%pCn	pll1
-	%pCr	1560000000
 
 	For printing struct clk structures. '%pC' and '%pCn' print the name
 	(Common Clock Framework) or address (legacy clock framework) of the
-	structure; '%pCr' prints the current clock rate.
+	structure.
 
 	Passed by reference.
 
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1391,9 +1391,6 @@ char *clock(char *buf, char *end, struct
 		return string(buf, end, NULL, spec);
 
 	switch (fmt[1]) {
-	case 'r':
-		return number(buf, end, clk_get_rate(clk), spec);
-
 	case 'n':
 	default:
 #ifdef CONFIG_COMMON_CLK