diff options
| author | Rasmus Villemoes <linux@rasmusvillemoes.dk> | 2015-11-06 16:30:35 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-11-06 17:50:42 -0800 |
| commit | d7ec9a05d6defda8432da574a2a888eed6fc29f6 (patch) | |
| tree | 453b5229f8165523c17dd4bd0baa04a281ced611 | |
| parent | 317dc34ab786d4f22bf7ed8ab546b9ae57f900d0 (diff) | |
lib/vsprintf.c: update documentation
%n is no longer just ignored; it results in early return from vsnprintf.
Also add a request to add test cases for future %p extensions.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | Documentation/printk-formats.txt | 12 | ||||
| -rw-r--r-- | lib/vsprintf.c | 7 |
2 files changed, 10 insertions, 9 deletions
diff --git a/Documentation/printk-formats.txt b/Documentation/printk-formats.txt index 9b8d7f746b1a..b784c270105f 100644 --- a/Documentation/printk-formats.txt +++ b/Documentation/printk-formats.txt @@ -23,6 +23,10 @@ Example: Reminder: sizeof() result is of type size_t. +The kernel's printf does not support %n. For obvious reasons, floating +point formats (%e, %f, %g, %a) are also not recognized. Use of any +unsupported specifier or length qualifier results in a WARN and early +return from vsnprintf. Raw pointer value SHOULD be printed with %p. The kernel supports the following extended format specifiers for pointer types: @@ -305,13 +309,9 @@ Command from struct task_struct Passed by reference. -Ignored argument: +If you add other %p extensions, please extend lib/test_printf.c with +one or more test cases, if at all feasible. - %n %n - - The argument passed will be ignored. In other words, literal "%n" will - be in the output and the argument will be considered for next format - specifier. Thank you for your cooperation and attention. diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 7848d53a5134..f9cee8e1233c 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -1448,7 +1448,6 @@ int kptr_restrict __read_mostly; * - 'Cn' For a clock, it prints the name (Common Clock Framework) or address * (legacy clock framework) of the clock * - 'Cr' For a clock, it prints the current rate of the clock - * - 'n' For ignored argument * * ** Please update also Documentation/printk-formats.txt when making changes ** * @@ -1814,8 +1813,10 @@ qualifier: * @fmt: The format string to use * @args: Arguments for the format string * - * This function follows C99 vsnprintf, but has some extensions: - * %n is ignored + * This function generally follows C99 vsnprintf, but has some + * extensions and a few limitations: + * + * %n is unsupported * %p* is handled by pointer() * * See pointer() or Documentation/printk-formats.txt for more |