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 <[email protected]>
Fixes: 900cca2944 ("lib/vsprintf: add %pC{,n,r} format specifiers for clocks")
Link: http://lkml.kernel.org/r/[email protected]
To: Jia-Ju Bai <[email protected]>
To: Jonathan Corbet <[email protected]>
To: Michael Turquette <[email protected]>
To: Stephen Boyd <[email protected]>
To: Zhang Rui <[email protected]>
To: Eduardo Valentin <[email protected]>
To: Eric Anholt <[email protected]>
To: Stefan Wahren <[email protected]>
To: Greg Kroah-Hartman <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Petr Mladek <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: Geert Uytterhoeven <[email protected]>
Cc: [email protected] # 4.1+
Signed-off-by: Geert Uytterhoeven <[email protected]>
Signed-off-by: Petr Mladek <[email protected]>

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.
 

lib/vsprintf.c

@@ -1446,9 +1446,6 @@ 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