linux-kernel - [PATCH 4/4] lib/vsprintf: Remove atomic-unsafe support for %pCr

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Date:   Fri,  1 Jun 2018 11:28:22 +0200
From:   Geert Uytterhoeven <geert+renesas@...der.be>
To:     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>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     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, linux-kernel@...r.kernel.org,
        Geert Uytterhoeven <geert+renesas@...der.be>
Subject: [PATCH 4/4] lib/vsprintf: Remove atomic-unsafe support for %pCr

"%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")
Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
---
 Documentation/core-api/printk-formats.rst | 3 +--
 lib/vsprintf.c                            | 3 ---
 2 files changed, 1 insertion(+), 5 deletions(-)

diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst
index eb30efdd2e789616..25dc591cb1108790 100644
--- a/Documentation/core-api/printk-formats.rst
+++ b/Documentation/core-api/printk-formats.rst
@@ -419,11 +419,10 @@ 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.
 
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 247a7e0bf24f6f74..a48aaa79d352313a 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1469,9 +1469,6 @@ char *clock(char *buf, char *end, struct clk *clk, struct printf_spec spec,
 		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
-- 
2.7.4