On Fri, 2015-10-02 at 14:28 +0200, Rasmus Villemoes wrote: > %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. Nice! Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> > > Signed-off-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx> > --- > applies on top of > lib-documentation-synchronize-%p-formatting-documentation.patch and > its -fix. > > Documentation/printk-formats.txt | 12 ++++++------ > 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 5028b044d0e5..488ee489279a 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 -- Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> Intel Finland Oy -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
