cpumask: add cpumask_scnprintf_len function

Add a new function cpumask_scnprintf_len() to return the number of
characters needed to display "len" cpumask bits.  The current method
of allocating NR_CPUS bytes is incorrect as what's really needed is
9 characters per 32-bit word of cpumask bits (8 hex digits plus the
seperator [','] or the terminating NULL.)  This function provides the
caller the means to allocate the correct string length.

Cc: Paul Jackson <pj@sgi.com>
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Mike Travis 2008-03-25 15:06:55 -07:00 committed by Ingo Molnar
parent 9f0e738f49
commit 30ca60c15a
3 changed files with 24 additions and 0 deletions

View file

@ -315,6 +315,22 @@ int bitmap_scnprintf(char *buf, unsigned int buflen,
}
EXPORT_SYMBOL(bitmap_scnprintf);
/**
* bitmap_scnprintf_len - return buffer length needed to convert
* bitmap to an ASCII hex string.
* @len: number of bits to be converted
*/
int bitmap_scnprintf_len(unsigned int len)
{
/* we need 9 chars per word for 32 bit words (8 hexdigits + sep/null) */
int bitslen = ALIGN(len, CHUNKSZ);
int wordlen = CHUNKSZ / 4;
int buflen = (bitslen / wordlen) * (wordlen + 1) * sizeof(char);
return buflen;
}
EXPORT_SYMBOL(bitmap_scnprintf_len);
/**
* __bitmap_parse - convert an ASCII hex string into a bitmap.
* @buf: pointer to buffer containing string.