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. Based on: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-x86.git Cc: Paul Jackson Signed-off-by: Mike Travis --- include/linux/bitmap.h | 1 + include/linux/cpumask.h | 7 +++++++ lib/bitmap.c | 16 ++++++++++++++++ 3 files changed, 24 insertions(+) --- linux.trees.git.orig/include/linux/bitmap.h +++ linux.trees.git/include/linux/bitmap.h @@ -108,6 +108,7 @@ extern int __bitmap_weight(const unsigne 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, --- linux.trees.git.orig/include/linux/cpumask.h +++ linux.trees.git/include/linux/cpumask.h @@ -273,6 +273,13 @@ static inline int __cpumask_scnprintf(ch 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, --- linux.trees.git.orig/lib/bitmap.c +++ linux.trees.git/lib/bitmap.c @@ -316,6 +316,22 @@ int bitmap_scnprintf(char *buf, unsigned 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. * @buflen: buffer size in bytes. If string is smaller than this -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/