Revision 2fdba6b085eb7068e9594cfa55ffe40466184b4d authored by Herbert Xu on 19 May 2005, 05:52:33 UTC, committed by David S. Miller on 19 May 2005, 05:52:33 UTC
Having frag_list members which holds wmem of an sk leads to nightmares
with partially cloned frag skb's.  The reason is that once you unleash
a skb with a frag_list that has individual sk ownerships into the stack
you can never undo those ownerships safely as they may have been cloned
by things like netfilter.  Since we have to undo them in order to make
skb_linearize happy this approach leads to a dead-end.

So let's go the other way and make this an invariant:

	For any skb on a frag_list, skb->sk must be NULL.

That is, the socket ownership always belongs to the head skb.
It turns out that the implementation is actually pretty simple.

The above invariant is actually violated in the following patch
for a short duration inside ip_fragment.  This is OK because the
offending frag_list member is either destroyed at the end of the
slow path without being sent anywhere, or it is detached from
the frag_list before being sent.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 parent d481020
Raw File
cmdline.c
/*
 * linux/lib/cmdline.c
 * Helper functions generally used for parsing kernel command line
 * and module options.
 *
 * Code and copyrights come from init/main.c and arch/i386/kernel/setup.c.
 *
 * This source code is licensed under the GNU General Public License,
 * Version 2.  See the file COPYING for more details.
 *
 * GNU Indent formatting options for this file: -kr -i8 -npsl -pcs
 *
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/string.h>


/**
 *	get_option - Parse integer from an option string
 *	@str: option string
 *	@pint: (output) integer value parsed from @str
 *
 *	Read an int from an option string; if available accept a subsequent
 *	comma as well.
 *
 *	Return values:
 *	0 : no int in string
 *	1 : int found, no subsequent comma
 *	2 : int found including a subsequent comma
 */

int get_option (char **str, int *pint)
{
	char *cur = *str;

	if (!cur || !(*cur))
		return 0;
	*pint = simple_strtol (cur, str, 0);
	if (cur == *str)
		return 0;
	if (**str == ',') {
		(*str)++;
		return 2;
	}

	return 1;
}

/**
 *	get_options - Parse a string into a list of integers
 *	@str: String to be parsed
 *	@nints: size of integer array
 *	@ints: integer array
 *
 *	This function parses a string containing a comma-separated
 *	list of integers.  The parse halts when the array is
 *	full, or when no more numbers can be retrieved from the
 *	string.
 *
 *	Return value is the character in the string which caused
 *	the parse to end (typically a null terminator, if @str is
 *	completely parseable).
 */
 
char *get_options(const char *str, int nints, int *ints)
{
	int res, i = 1;

	while (i < nints) {
		res = get_option ((char **)&str, ints + i);
		if (res == 0)
			break;
		i++;
		if (res == 1)
			break;
	}
	ints[0] = i - 1;
	return (char *)str;
}

/**
 *	memparse - parse a string with mem suffixes into a number
 *	@ptr: Where parse begins
 *	@retptr: (output) Pointer to next char after parse completes
 *
 *	Parses a string into a number.  The number stored at @ptr is
 *	potentially suffixed with %K (for kilobytes, or 1024 bytes),
 *	%M (for megabytes, or 1048576 bytes), or %G (for gigabytes, or
 *	1073741824).  If the number is suffixed with K, M, or G, then
 *	the return value is the number multiplied by one kilobyte, one
 *	megabyte, or one gigabyte, respectively.
 */

unsigned long long memparse (char *ptr, char **retptr)
{
	unsigned long long ret = simple_strtoull (ptr, retptr, 0);

	switch (**retptr) {
	case 'G':
	case 'g':
		ret <<= 10;
	case 'M':
	case 'm':
		ret <<= 10;
	case 'K':
	case 'k':
		ret <<= 10;
		(*retptr)++;
	default:
		break;
	}
	return ret;
}


EXPORT_SYMBOL(memparse);
EXPORT_SYMBOL(get_option);
EXPORT_SYMBOL(get_options);
back to top