vsprintf: Consolidate handling of unknown pointer specifiers

There are few printk formats that make sense only with two or more
specifiers. Also some specifiers make sense only when a kernel feature
is enabled.

The handling of unknown specifiers is inconsistent and not helpful.
Using WARN() looks like an overkill for this type of error. pr_warn()
is not good either. It would by handled via printk_safe buffer and
it might be hard to match it with the problematic string.

A reasonable compromise seems to be writing the unknown format specifier
into the original string with a question mark, for example (%pC?).
It should be self-explaining enough. Note that it is in brackets
to follow the (null) style.

Note that it introduces a warning about that test_hashed() function
is unused. It is going to be used again by a later patch.

Link: http://lkml.kernel.org/r/[email protected]
To: Rasmus Villemoes <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: "Tobin C . Harding" <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: [email protected]
Reviewed-by: Sergey Senozhatsky <[email protected]>
Reviewed-by: Andy Shevchenko <[email protected]>
Signed-off-by: Petr Mladek <[email protected]>

1 files changed, 1 insertions, 2 deletions

diff --git a/lib/test_printf.c b/lib/test_printf.c
index 659b6cc0d483..250ee864b8b8 100644
--- a/lib/test_printf.c
+++ b/lib/test_printf.c
@@ -462,8 +462,7 @@ struct_rtc_time(void)
 		.tm_year = 118,
 	};
 
-	test_hashed("%pt", &tm);
-
+	test("(%ptR?)", "%pt", &tm);
 	test("2018-11-26T05:35:43", "%ptR", &tm);
 	test("0118-10-26T05:35:43", "%ptRr", &tm);
 	test("05:35:43|2018-11-26", "%ptRt|%ptRd", &tm, &tm);