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Commit 5e4ee7b1 authored by Martin Kletzander's avatar Martin Kletzander Committed by Linus Torvalds
Browse files

printk: synchronize %p formatting documentation 



Move all pointer-formatting documentation to one place in the code and one
place in the documentation instead of keeping it in three places with
different level of completeness.  Documentation/printk-formats.txt has
detailed information about each modifier, docstring above pointer() has
short descriptions of them (as that is the function dealing with %p) and
docstring above vsprintf() is removed as redundant.  Both docstrings in
the code that were modified are updated with a reminder of updating the
documentation upon any further change.

[akpm@linux-foundation.org: fix comment]
Signed-off-by: default avatarMartin Kletzander <mkletzan@redhat.com>
Reviewed-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3e406b1d

Documentation/printk-formats.txt

+29 −0
Original line number Diff line number Diff line
@@ -119,6 +119,7 @@ Raw buffer as an escaped string: 
	If field width is omitted the 1 byte only will be escaped.



Raw buffer as a hex string:



	%*ph	00 01 02  ...  3f

	%*phC	00:01:02: ... :3f

	%*phD	00-01-02- ... -3f
@@ -234,6 +235,7 @@ UUID/GUID addresses: 
	Passed by reference.



dentry names:



	%pd{,2,3,4}

	%pD{,2,3,4}
@@ -256,6 +258,8 @@ struct va_format: 
		va_list *va;

	};



	Implements a "recursive vsnprintf".



	Do not use this feature without some mechanism to verify the

	correctness of the format string and va_list arguments.
@@ -284,6 +288,31 @@ bitmap and its derivatives such as cpumask and nodemask: 


	Passed by reference.



Network device features:



	%pNF	0x000000000000c000



	For printing netdev_features_t.



	Passed by reference.



Command from struct task_struct



	%pT	ls



	For printing executable name excluding path from struct

	task_struct.



	Passed by reference.



Ignored argument:



	%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.

lib/vsprintf.c

+8 −32
Original line number Diff line number Diff line
@@ -1448,6 +1448,9 @@ 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 **

 *

 * Note: The difference between 'S' and 'F' is that on ia64 and ppc64

 * function pointers are really function descriptors, which contain a
@@ -1812,40 +1815,13 @@ int format_decode(const char *fmt, struct printf_spec *spec) 
 * @args: Arguments for the format string

 *

 * This function follows C99 vsnprintf, but has some extensions:

 * %pS output the name of a text symbol with offset

 * %ps output the name of a text symbol without offset

 * %pF output the name of a function pointer with its offset

 * %pf output the name of a function pointer without its offset

 * %pB output the name of a backtrace symbol with its offset

 * %pR output the address range in a struct resource with decoded flags

 * %pr output the address range in a struct resource with raw flags

 * %pb output the bitmap with field width as the number of bits

 * %pbl output the bitmap as range list with field width as the number of bits

 * %pM output a 6-byte MAC address with colons

 * %pMR output a 6-byte MAC address with colons in reversed order

 * %pMF output a 6-byte MAC address with dashes

 * %pm output a 6-byte MAC address without colons

 * %pmR output a 6-byte MAC address without colons in reversed order

 * %pI4 print an IPv4 address without leading zeros

 * %pi4 print an IPv4 address with leading zeros

 * %pI6 print an IPv6 address with colons

 * %pi6 print an IPv6 address without colons

 * %pI6c print an IPv6 address as specified by RFC 5952

 * %pIS depending on sa_family of 'struct sockaddr *' print IPv4/IPv6 address

 * %piS depending on sa_family of 'struct sockaddr *' print IPv4/IPv6 address

 * %pU[bBlL] print a UUID/GUID in big or little endian using lower or upper

 *   case.

 * %*pE[achnops] print an escaped buffer

 * %*ph[CDN] a variable-length hex string with a separator (supports up to 64

 *           bytes of the input)

 * %pC output the name (Common Clock Framework) or address (legacy clock

 *     framework) of a clock

 * %pCn output the name (Common Clock Framework) or address (legacy clock

 *      framework) of a clock

 * %pCr output the current rate of a clock

 * %n is ignored

 * %p* is handled by pointer()

 *

 * See pointer() or Documentation/printk-formats.txt for more

 * extensive description.

 *

 * ** Please update Documentation/printk-formats.txt when making changes **

 * ** Please update the documentation in both places when making changes **

 *

 * The return value is the number of characters which would

 * be generated for the given input, excluding the trailing