[PATCH 05/10] cpumask: Add cpumask_scnprintf_len function

Mike Travis
2008-03-25T02:21:05Z

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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.

Based on linux-2.6.25-rc5-mm1

Cc: Paul Jackson <pj@sgi.com>

Signed-off-by: Mike Travis <travis@sgi.com>
---
include/linux/bitmap.h | 1 +
include/linux/cpumask.h | 7 +++++++
lib/bitmap.c | 16 ++++++++++++++++
3 files changed, 24 insertions(+)

--- linux-2.6.25-rc5.orig/include/linux/bitmap.h
+++ linux-2.6.25-rc5/include/linux/bitmap.h
@@ -110,6 +110,7 @@ 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-2.6.25-rc5.orig/include/linux/cpumask.h
+++ linux-2.6.25-rc5/include/linux/cpumask.h
@@ -277,6 +277,13 @@ 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-2.6.25-rc5.orig/lib/bitmap.c
+++ linux-2.6.25-rc5/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

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