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cpumask: add cpumask_scnprintf_len function

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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
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1
include/linux/bitmap.h
View file

@ -108,6 +108,7 @@ extern int __bitmap_weight(const unsigned long *bitmap, int bits);
extern int bitmap_scnprintf(char *buf, unsigned int len,
const unsigned long *src, int nbits);
extern int bitmap_scnprintf_len(unsigned int len);
extern int __bitmap_parse(const char *buf, unsigned int buflen, int is_user,
unsigned long *dst, int nbits);
extern int bitmap_parse_user(const char __user *ubuf, unsigned int ulen,

7
include/linux/cpumask.h
View file

@ -273,6 +273,13 @@ static inline int __cpumask_scnprintf(char *buf, int len,
return bitmap_scnprintf(buf, len, srcp->bits, nbits);
}
#define cpumask_scnprintf_len(len) \
__cpumask_scnprintf_len((len))
static inline int __cpumask_scnprintf_len(int len)
{
return bitmap_scnprintf_len(len);
}
#define cpumask_parse_user(ubuf, ulen, dst) \
__cpumask_parse_user((ubuf), (ulen), &(dst), NR_CPUS)
static inline int __cpumask_parse_user(const char __user *buf, int len,

16
lib/bitmap.c
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.