[PATCH] cpusets: bitmap and mask remap operators

In the forthcoming task migration support, a key calculation will be
mapping cpu and node numbers from the old set to the new set while
preserving cpuset-relative offset.

For example, if a task and its pages on nodes 8-11 are being migrated to
nodes 24-27, then pages on node 9 (the 2nd node in the old set) should be
moved to node 25 (the 2nd node in the new set.)

As with other bitmap operations, the proper way to code this is to provide
the underlying calculation in lib/bitmap.c, and then to provide the usual
cpumask and nodemask wrappers.

This patch provides that.  These operations are termed 'remap' operations.
Both remapping a single bit and a set of bits is supported.

Signed-off-by: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 20 insertions, 0 deletions

diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index 9bdba81..13e9f4a 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -12,6 +12,8 @@
  * see bitmap_scnprintf() and bitmap_parse() in lib/bitmap.c.
  * For details of cpulist_scnprintf() and cpulist_parse(), see
  * bitmap_scnlistprintf() and bitmap_parselist(), also in bitmap.c.
+ * For details of cpu_remap(), see bitmap_bitremap in lib/bitmap.c
+ * For details of cpus_remap(), see bitmap_remap in lib/bitmap.c.
  *
  * The available cpumask operations are:
  *
@@ -50,6 +52,8 @@
  * int cpumask_parse(ubuf, ulen, mask)	Parse ascii string as cpumask
  * int cpulist_scnprintf(buf, len, mask) Format cpumask as list for printing
  * int cpulist_parse(buf, map)		Parse ascii string as cpulist
+ * int cpu_remap(oldbit, old, new)	newbit = map(old, new)(oldbit)
+ * int cpus_remap(dst, src, old, new)	*dst = map(old, new)(src)
  *
  * for_each_cpu_mask(cpu, mask)		for-loop cpu over mask
  *
@@ -294,6 +298,22 @@ static inline int __cpulist_parse(const char *buf, cpumask_t *dstp, int nbits)
 	return bitmap_parselist(buf, dstp->bits, nbits);
 }
 
+#define cpu_remap(oldbit, old, new) \
+		__cpu_remap((oldbit), &(old), &(new), NR_CPUS)
+static inline int __cpu_remap(int oldbit,
+		const cpumask_t *oldp, const cpumask_t *newp, int nbits)
+{
+	return bitmap_bitremap(oldbit, oldp->bits, newp->bits, nbits);
+}
+
+#define cpus_remap(dst, src, old, new) \
+		__cpus_remap(&(dst), &(src), &(old), &(new), NR_CPUS)
+static inline void __cpus_remap(cpumask_t *dstp, const cpumask_t *srcp,
+		const cpumask_t *oldp, const cpumask_t *newp, int nbits)
+{
+	bitmap_remap(dstp->bits, srcp->bits, oldp->bits, newp->bits, nbits);
+}
+
 #if NR_CPUS > 1
 #define for_each_cpu_mask(cpu, mask)		\
 	for ((cpu) = first_cpu(mask);		\