[PATCH] cpumask: bitmap cleanup preparation for cpumask overhaul

From: Paul Jackson <pj@sgi.com>

Document the bitmap bit model and handling of unused bits.

Tighten up bitmap so it does not generate nonzero bits in the unused tail if
it is not given any on input.

Add intersects, subset, xor and andnot operators.  Change bitmap_complement to
take two operands.

Add a couple of missing 'const' qualifiers on bitops test_bit and bitmap_equal
args.

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

8 files changed, 102 insertions, 21 deletions

diff --git a/arch/x86_64/kernel/smpboot.c b/arch/x86_64/kernel/smpboot.c
index ba2cba68da14..06937402b31c 100644
--- a/arch/x86_64/kernel/smpboot.c
+++ b/arch/x86_64/kernel/smpboot.c
@@ -827,7 +827,7 @@ static void __init smp_boot_cpus(unsigned int max_cpus)
 		if (apicid == boot_cpu_id || (apicid == BAD_APICID))
 			continue;
 
-		if (!cpu_isset(apicid, phys_cpu_present_map))
+		if (!physid_isset(apicid, phys_cpu_present_map))
 			continue;
 		if ((max_cpus >= 0) && (max_cpus <= cpucount+1))
 			continue;
diff --git a/include/asm-generic/bitops.h b/include/asm-generic/bitops.h
index 23ac5227b702..ce31b739fd80 100644
--- a/include/asm-generic/bitops.h
+++ b/include/asm-generic/bitops.h
@@ -42,7 +42,7 @@ extern __inline__ int clear_bit(int nr, long * addr)
 	return retval;
 }
 
-extern __inline__ int test_bit(int nr, long * addr)
+extern __inline__ int test_bit(int nr, const unsigned long * addr)
 {
 	int	mask;
 
diff --git a/include/asm-generic/cpumask_array.h b/include/asm-generic/cpumask_array.h
index ddd6e1185dba..1be08ae2e93b 100644
--- a/include/asm-generic/cpumask_array.h
+++ b/include/asm-generic/cpumask_array.h
@@ -17,7 +17,7 @@
 #define cpus_and(dst,src1,src2)	bitmap_and((dst).mask,(src1).mask, (src2).mask, NR_CPUS)
 #define cpus_or(dst,src1,src2)	bitmap_or((dst).mask, (src1).mask, (src2).mask, NR_CPUS)
 #define cpus_clear(map)		bitmap_zero((map).mask, NR_CPUS)
-#define cpus_complement(map)	bitmap_complement((map).mask, NR_CPUS)
+#define cpus_complement(map)	bitmap_complement((map).mask, (map).mask, NR_CPUS)
 #define cpus_equal(map1, map2)	bitmap_equal((map1).mask, (map2).mask, NR_CPUS)
 #define cpus_empty(map)		bitmap_empty(map.mask, NR_CPUS)
 #define cpus_addr(map)		((map).mask)
diff --git a/include/asm-i386/mpspec.h b/include/asm-i386/mpspec.h
index b2cc2feeb8a4..31a9717c1a8b 100644
--- a/include/asm-i386/mpspec.h
+++ b/include/asm-i386/mpspec.h
@@ -53,7 +53,7 @@ typedef struct physid_mask physid_mask_t;
 #define physids_and(dst, src1, src2)		bitmap_and((dst).mask, (src1).mask, (src2).mask, MAX_APICS)
 #define physids_or(dst, src1, src2)		bitmap_or((dst).mask, (src1).mask, (src2).mask, MAX_APICS)
 #define physids_clear(map)			bitmap_zero((map).mask, MAX_APICS)
-#define physids_complement(map)			bitmap_complement((map).mask, MAX_APICS)
+#define physids_complement(map)			bitmap_complement((map).mask, (map).mask, MAX_APICS)
 #define physids_empty(map)			bitmap_empty((map).mask, MAX_APICS)
 #define physids_equal(map1, map2)		bitmap_equal((map1).mask, (map2).mask, MAX_APICS)
 #define physids_weight(map)			bitmap_weight((map).mask, MAX_APICS)
diff --git a/include/asm-x86_64/mpspec.h b/include/asm-x86_64/mpspec.h
index fd707a6a8bcd..a9a6f16672f2 100644
--- a/include/asm-x86_64/mpspec.h
+++ b/include/asm-x86_64/mpspec.h
@@ -212,7 +212,7 @@ typedef struct physid_mask physid_mask_t;
 #define physids_and(dst, src1, src2)		bitmap_and((dst).mask, (src1).mask, (src2).mask, MAX_APICS)
 #define physids_or(dst, src1, src2)		bitmap_or((dst).mask, (src1).mask, (src2).mask, MAX_APICS)
 #define physids_clear(map)			bitmap_zero((map).mask, MAX_APICS)
-#define physids_complement(map)			bitmap_complement((map).mask, MAX_APICS)
+#define physids_complement(map)			bitmap_complement((map).mask, (map).mask, MAX_APICS)
 #define physids_empty(map)			bitmap_empty((map).mask, MAX_APICS)
 #define physids_equal(map1, map2)		bitmap_equal((map1).mask, (map2).mask, MAX_APICS)
 #define physids_weight(map)			bitmap_weight((map).mask, MAX_APICS)
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index c301d121c8d0..bc93e0167a81 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -13,8 +13,8 @@
 int bitmap_empty(const unsigned long *bitmap, int bits);
 int bitmap_full(const unsigned long *bitmap, int bits);
 int bitmap_equal(const unsigned long *bitmap1,
-			unsigned long *bitmap2, int bits);
-void bitmap_complement(unsigned long *bitmap, int bits);
+			const unsigned long *bitmap2, int bits);
+void bitmap_complement(unsigned long *dst, const unsigned long *src, int bits);
 
 static inline void bitmap_zero(unsigned long *bitmap, int bits)
 {
@@ -41,6 +41,14 @@ void bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
 			const unsigned long *bitmap2, int bits);
 void bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
 			const unsigned long *bitmap2, int bits);
+void bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
+			const unsigned long *bitmap2, int bits);
+void bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
+			const unsigned long *bitmap2, int bits);
+int bitmap_intersects(const unsigned long *bitmap1,
+			const unsigned long *bitmap2, int bits);
+int bitmap_subset(const unsigned long *bitmap1,
+			const unsigned long *bitmap2, int bits);
 int bitmap_weight(const unsigned long *bitmap, int bits);
 int bitmap_scnprintf(char *buf, unsigned int buflen,
 			const unsigned long *maskp, int bits);
diff --git a/lib/bitmap.c b/lib/bitmap.c
index 779d30365e46..a96433e37102 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -12,6 +12,26 @@
 #include <asm/bitops.h>
 #include <asm/uaccess.h>
 
+/*
+ * bitmaps provide an array of bits, implemented using an an
+ * array of unsigned longs.  The number of valid bits in a
+ * given bitmap need not be an exact multiple of BITS_PER_LONG.
+ *
+ * The possible unused bits in the last, partially used word
+ * of a bitmap are 'don't care'.  The implementation makes
+ * no particular effort to keep them zero.  It ensures that
+ * their value will not affect the results of any operation.
+ * The bitmap operations that return Boolean (bitmap_empty,
+ * for example) or scalar (bitmap_weight, for example) results
+ * carefully filter out these unused bits from impacting their
+ * results.
+ *
+ * These operations actually hold to a slightly stronger rule:
+ * if you don't input any bitmaps to these ops that have some
+ * unused bits set, then they won't output any set unused bits
+ * in output bitmaps.
+ */
+
 int bitmap_empty(const unsigned long *bitmap, int bits)
 {
 	int k, lim = bits/BITS_PER_LONG;
@@ -43,7 +63,7 @@ int bitmap_full(const unsigned long *bitmap, int bits)
 EXPORT_SYMBOL(bitmap_full);
 
 int bitmap_equal(const unsigned long *bitmap1,
-		unsigned long *bitmap2, int bits)
+		const unsigned long *bitmap2, int bits)
 {
 	int k, lim = bits/BITS_PER_LONG;
 	for (k = 0; k < lim; ++k)
@@ -59,13 +79,14 @@ int bitmap_equal(const unsigned long *bitmap1,
 }
 EXPORT_SYMBOL(bitmap_equal);
 
-void bitmap_complement(unsigned long *bitmap, int bits)
+void bitmap_complement(unsigned long *dst, const unsigned long *src, int bits)
 {
-	int k;
-	int nr = BITS_TO_LONGS(bits);
+	int k, lim = bits/BITS_PER_LONG;
+	for (k = 0; k < lim; ++k)
+		dst[k] = ~src[k];
 
-	for (k = 0; k < nr; ++k)
-		bitmap[k] = ~bitmap[k];
+	if (bits % BITS_PER_LONG)
+		dst[k] = ~src[k] & ((1UL << (bits % BITS_PER_LONG)) - 1);
 }
 EXPORT_SYMBOL(bitmap_complement);
 
@@ -173,6 +194,60 @@ void bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
 }
 EXPORT_SYMBOL(bitmap_or);
 
+void bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
+				const unsigned long *bitmap2, int bits)
+{
+	int k;
+	int nr = BITS_TO_LONGS(bits);
+
+	for (k = 0; k < nr; k++)
+		dst[k] = bitmap1[k] ^ bitmap2[k];
+}
+EXPORT_SYMBOL(bitmap_xor);
+
+void bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
+				const unsigned long *bitmap2, int bits)
+{
+	int k;
+	int nr = BITS_TO_LONGS(bits);
+
+	for (k = 0; k < nr; k++)
+		dst[k] = bitmap1[k] & ~bitmap2[k];
+}
+EXPORT_SYMBOL(bitmap_andnot);
+
+int bitmap_intersects(const unsigned long *bitmap1,
+				const unsigned long *bitmap2, int bits)
+{
+	int k, lim = bits/BITS_PER_LONG;
+	for (k = 0; k < lim; ++k)
+		if (bitmap1[k] & bitmap2[k])
+			return 1;
+
+	if (bits % BITS_PER_LONG)
+		if ((bitmap1[k] & bitmap2[k]) &
+				((1UL << (bits % BITS_PER_LONG)) - 1))
+			return 1;
+	return 0;
+}
+EXPORT_SYMBOL(bitmap_intersects);
+
+int bitmap_subset(const unsigned long *bitmap1,
+				const unsigned long *bitmap2, int bits)
+{
+	int k, lim = bits/BITS_PER_LONG;
+	for (k = 0; k < lim; ++k)
+		if (bitmap1[k] & ~bitmap2[k])
+			return 0;
+
+	if (bits % BITS_PER_LONG)
+		if ((bitmap1[k] & ~bitmap2[k]) &
+				((1UL << (bits % BITS_PER_LONG)) - 1))
+			return 0;
+	return 1;
+}
+EXPORT_SYMBOL(bitmap_subset);
+
 #if BITS_PER_LONG == 32
 int bitmap_weight(const unsigned long *bitmap, int bits)
 {
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 4f1fc840550a..d06eabbf74f0 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -93,14 +93,12 @@ static struct mempolicy default_policy = {
 /* Check if all specified nodes are online */
 static int nodes_online(unsigned long *nodes)
 {
-	DECLARE_BITMAP(offline, MAX_NUMNODES);
-
-	bitmap_copy(offline, node_online_map, MAX_NUMNODES);
-	if (bitmap_empty(offline, MAX_NUMNODES))
-		set_bit(0, offline);
-	bitmap_complement(offline, MAX_NUMNODES);
-	bitmap_and(offline, offline, nodes, MAX_NUMNODES);
-	if (!bitmap_empty(offline, MAX_NUMNODES))
+	DECLARE_BITMAP(online2, MAX_NUMNODES);
+
+	bitmap_copy(online2, node_online_map, MAX_NUMNODES);
+	if (bitmap_empty(online2, MAX_NUMNODES))
+		set_bit(0, online2);
+	if (!bitmap_subset(nodes, online2, MAX_NUMNODES))
 		return -EINVAL;
 	return 0;
 }