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>
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index acad110..1dbe074 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -108,6 +108,7 @@
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,
diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index 7047f58..67e0e38 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -273,6 +273,13 @@
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,
diff --git a/lib/bitmap.c b/lib/bitmap.c
index 2c9242e..a6939e1 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -316,6 +316,22 @@
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
