Date:	Mon, 21 Sep 2015 12:18:07 +0300
From:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:	Martin Kletzander <mkletzan@...hat.com>, linux-doc@...r.kernel.org
Cc:	Jonathan Corbet <corbet@....net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Rasmus Villemoes <linux@...musvillemoes.dk>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
	Stephen Boyd <sboyd@...eaurora.org>, Tejun Heo <tj@...nel.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] lib: Documentation: Synchronize %p formatting
 documentation

On Mon, 2015-09-21 at 11:13 +0200, Martin Kletzander wrote:
> Move all pointer-formatting documentation to one place instead of
> keeping it in three places with different level of completeness.
> 

I think we still need at least one in the code. I, for example, often
read it from the actual c-file, not from documentation.

So, good change for printk-formats.txt, but not okay for me for the
vsprintf.c.

> Signed-off-by: Martin Kletzander <mkletzan@...hat.com>
> ---
>  Documentation/printk-formats.txt |  27 +++++++++
>  lib/vsprintf.c                   | 123 ++---------------------------
> ----------
>  2 files changed, 32 insertions(+), 118 deletions(-)
> 
> diff --git a/Documentation/printk-formats.txt b/Documentation/printk
> -formats.txt
> index 2ec6d84f391c..c85e27264a2b 100644
> --- a/Documentation/printk-formats.txt
> +++ b/Documentation/printk-formats.txt
> @@ -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}
> 
> @@ -264,6 +266,8 @@ 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.
> 
> @@ -292,6 +296,29 @@ 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:
> +
> +	%pn
> +
> +	The argument passed will be ignored.
> +
>  Thank you for your cooperation and attention.
> 
> 
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> index becd87facf48..6e358dc81ef0 100644
> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> @@ -1383,91 +1383,9 @@ int kptr_restrict __read_mostly;
>   * by an extra set of alphanumeric characters that are extended 
> format
>   * specifiers.
>   *
> - * Right now we handle:
> + * All format specifiers are documented in Documentation/printk
> -formats.txt.
>   *
> - * - 'F' For symbolic function descriptor pointers with offset
> - * - 'f' For simple symbolic function names without offset
> - * - 'S' For symbolic direct pointers with offset
> - * - 's' For symbolic direct pointers without offset
> - * - '[FfSs]R' as above with __builtin_extract_return_addr() 
> translation
> - * - 'B' For backtraced symbolic direct pointers with offset
> - * - 'R' For decoded struct resource, e.g., [mem 0x0-0x1f 64bit 
> pref]
> - * - 'r' For raw struct resource, e.g., [mem 0x0-0x1f flags 0x201]
> - * - 'b[l]' For a bitmap, the number of bits is determined by the 
> field
> - *       width which must be explicitly specified either as part of 
> the
> - *       format string '%32b[l]' or through '%*b[l]', [l] selects
> - *       range-list format instead of hex format
> - * - 'M' For a 6-byte MAC address, it prints the address in the
> - *       usual colon-separated hex notation
> - * - 'm' For a 6-byte MAC address, it prints the hex address without 
> colons
> - * - 'MF' For a 6-byte MAC FDDI address, it prints the address
> - *       with a dash-separated hex notation
> - * - '[mM]R' For a 6-byte MAC address, Reverse order (Bluetooth)
> - * - 'I' [46] for IPv4/IPv6 addresses printed in the usual way
> - *       IPv4 uses dot-separated decimal without leading 0's 
> (1.2.3.4)
> - *       IPv6 uses colon separated network-order 16 bit hex with 
> leading 0's
> - *       [S][pfs]
> - *       Generic IPv4/IPv6 address (struct sockaddr *) that falls 
> back to
> - *       [4] or [6] and is able to print port [p], flowinfo [f], 
> scope [s]
> - * - 'i' [46] for 'raw' IPv4/IPv6 addresses
> - *       IPv6 omits the colons (01020304...0f)
> - *       IPv4 uses dot-separated decimal with leading 0's 
> (010.123.045.006)
> - *       [S][pfs]
> - *       Generic IPv4/IPv6 address (struct sockaddr *) that falls 
> back to
> - *       [4] or [6] and is able to print port [p], flowinfo [f], 
> scope [s]
> - * - '[Ii][4S][hnbl]' IPv4 addresses in host, network, big or little 
> endian order
> - * - 'I[6S]c' for IPv6 addresses printed as specified by
> - *       http://tools.ietf.org/html/rfc5952
> - * - 'E[achnops]' For an escaped buffer, where rules are defined by 
> combination
> - *                of the following flags (see string_escape_mem() 
> for the
> - *                details):
> - *                  a - ESCAPE_ANY
> - *                  c - ESCAPE_SPECIAL
> - *                  h - ESCAPE_HEX
> - *                  n - ESCAPE_NULL
> - *                  o - ESCAPE_OCTAL
> - *                  p - ESCAPE_NP
> - *                  s - ESCAPE_SPACE
> - *                By default ESCAPE_ANY_NP is used.
> - * - 'U' For a 16 byte UUID/GUID, it prints the UUID/GUID in the 
> form
> - *       "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
> - *       Options for %pU are:
> - *         b big endian lower case hex (default)
> - *         B big endian UPPER case hex
> - *         l little endian lower case hex
> - *         L little endian UPPER case hex
> - *           big endian output byte order is:
> - *             [0][1][2][3]-[4][5]-[6][7]-[8][9]
> -[10][11][12][13][14][15]
> - *           little endian output byte order is:
> - *             [3][2][1][0]-[5][4]-[7][6]-[8][9]
> -[10][11][12][13][14][15]
> - * - 'V' For a struct va_format which contains a format string * and 
> va_list *,
> - *       call vsnprintf(->format, *->va_list).
> - *       Implements a "recursive vsnprintf".
> - *       Do not use this feature without some mechanism to verify 
> the
> - *       correctness of the format string and va_list arguments.
> - * - 'K' For a kernel pointer that should be hidden from 
> unprivileged users
> - * - 'NF' For a netdev_features_t
> - * - 'h[CDN]' For a variable-length buffer, it prints it as a hex 
> string with
> - *            a certain separator (' ' by default):
> - *              C colon
> - *              D dash
> - *              N no separator
> - *            The maximum supported length is 64 bytes of the input. 
> Consider
> - *            to use print_hex_dump() for the larger input.
> - * - 'a[pd]' For address types [p] phys_addr_t, [d] dma_addr_t and 
> derivatives
> - *           (default assumed to be phys_addr_t, passed by 
> reference)
> - * - 'd[234]' For a dentry name (optionally 2-4 last components)
> - * - 'D[234]' Same as 'd' but for a struct file
> - * - 'C' For a clock, it prints the name (Common Clock Framework) or 
> address
> - *       (legacy clock framework) of the clock
> - * - '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
> - * - 'T' task_struct->comm
> - *
> - * Note: The difference between 'S' and 'F' is that on ia64 and 
> ppc64
> - * function pointers are really function descriptors, which contain 
> a
> - * pointer to the real address.
> + * ** Please update the documentation when making changes **
>   */
>  static noinline_for_stack
>  char *pointer(const char *fmt, char *buf, char *end, void *ptr,
> @@ -1829,41 +1747,10 @@ qualifier:
>   * @fmt: The format string to use
>   * @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
> + * This function follows C99 vsnprintf, but has some extensions.
> + * All format specifiers are documented in Documentation/printk
> -formats.txt.
>   *
> - * ** Please update Documentation/printk-formats.txt when making 
> changes **
> + * ** Please update the documentation when making changes **
>   *
>   * The return value is the number of characters which would
>   * be generated for the given input, excluding the trailing

-- 
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Intel Finland Oy
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