cpumask: introduce for_each_cpu_or

mainline inclusion
from mainline-v6.3-rc4
commit 1470afef
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I6VS35

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1470afefc3c42df5d1662f87d079b46651bdc95b

--------------------------------

Equivalent of for_each_cpu_and, except it ORs the two masks together
so it iterates all the CPUs present in either mask.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NDarrick J. Wong <djwong@kernel.org>
Signed-off-by: NDarrick J. Wong <djwong@kernel.org>
Signed-off-by: NZeng Heng <zengheng4@huawei.com>

include/asm-generic/bitops/find.h

@@ -97,4 +97,42 @@ extern unsigned long find_next_clump8(unsigned long *clump,
 #define find_first_clump8(clump, bits, size) \
 	find_next_clump8((clump), (bits), (size), 0)
 
+unsigned long _find_next_or_bit(const unsigned long *addr1, const unsigned long *addr2,
+					unsigned long nbits, unsigned long start);
+
+#ifndef find_next_or_bit
+/**
+ * find_next_or_bit - find the next set bit in either memory regions
+ * @addr1: The first address to base the search on
+ * @addr2: The second address to base the search on
+ * @size: The bitmap size in bits
+ * @offset: The bitnumber to start searching at
+ *
+ * Returns the bit number for the next set bit
+ * If no bits are set, returns @size.
+ */
+static inline
+unsigned long find_next_or_bit(const unsigned long *addr1,
+		const unsigned long *addr2, unsigned long size,
+		unsigned long offset)
+{
+	if (small_const_nbits(size)) {
+		unsigned long val;
+
+		if (unlikely(offset >= size))
+			return size;
+
+		val = (*addr1 | *addr2) & GENMASK(size - 1, offset);
+		return val ? __ffs(val) : size;
+	}
+
+	return _find_next_or_bit(addr1, addr2, size, offset);
+}
+#endif
+
+#define for_each_or_bit(bit, addr1, addr2, size) \
+	for ((bit) = 0;									\
+	     (bit) = find_next_or_bit((addr1), (addr2), (size), (bit)), (bit) < (size);\
+	     (bit)++)
+
 #endif /*_ASM_GENERIC_BITOPS_FIND_H_ */

include/linux/cpumask.h

@@ -325,6 +325,58 @@ extern int cpumask_next_wrap(int n, const struct cpumask *mask, int start, bool
 		(cpu) < nr_cpu_ids;)
 #endif /* SMP */
 
+/*
+ * We have several different "preferred sizes" for the cpumask
+ * operations, depending on operation.
+ *
+ * For example, the bitmap scanning and operating operations have
+ * optimized routines that work for the single-word case, but only when
+ * the size is constant. So if NR_CPUS fits in one single word, we are
+ * better off using that small constant, in order to trigger the
+ * optimized bit finding. That is 'small_cpumask_size'.
+ *
+ * The clearing and copying operations will similarly perform better
+ * with a constant size, but we limit that size arbitrarily to four
+ * words. We call this 'large_cpumask_size'.
+ *
+ * Finally, some operations just want the exact limit, either because
+ * they set bits or just don't have any faster fixed-sized versions. We
+ * call this just 'nr_cpumask_bits'.
+ *
+ * Note that these optional constants are always guaranteed to be at
+ * least as big as 'nr_cpu_ids' itself is, and all our cpumask
+ * allocations are at least that size (see cpumask_size()). The
+ * optimization comes from being able to potentially use a compile-time
+ * constant instead of a run-time generated exact number of CPUs.
+ */
+#if NR_CPUS <= BITS_PER_LONG
+  #define small_cpumask_bits ((unsigned int)NR_CPUS)
+  #define large_cpumask_bits ((unsigned int)NR_CPUS)
+#elif NR_CPUS <= 4*BITS_PER_LONG
+  #define small_cpumask_bits nr_cpu_ids
+  #define large_cpumask_bits ((unsigned int)NR_CPUS)
+#else
+  #define small_cpumask_bits nr_cpu_ids
+  #define large_cpumask_bits nr_cpu_ids
+#endif
+
+/**
+ * for_each_cpu_or - iterate over every cpu present in either mask
+ * @cpu: the (optionally unsigned) integer iterator
+ * @mask1: the first cpumask pointer
+ * @mask2: the second cpumask pointer
+ *
+ * This saves a temporary CPU mask in many places.  It is equivalent to:
+ *	struct cpumask tmp;
+ *	cpumask_or(&tmp, &mask1, &mask2);
+ *	for_each_cpu(cpu, &tmp)
+ *		...
+ *
+ * After the loop, cpu is >= nr_cpu_ids.
+ */
+#define for_each_cpu_or(cpu, mask1, mask2)				\
+	for_each_or_bit(cpu, cpumask_bits(mask1), cpumask_bits(mask2), small_cpumask_bits)
+
 #define CPU_BITS_NONE						\
 {								\
 	[0 ... BITS_TO_LONGS(NR_CPUS)-1] = 0UL			\

lib/find_bit.c

@@ -81,6 +81,43 @@ unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
 EXPORT_SYMBOL(find_next_bit);
 #endif
 
+/*
+ * Common helper for find_next_bit() function family
+ * @FETCH: The expression that fetches and pre-processes each word of bitmap(s)
+ * @MUNGE: The expression that post-processes a word containing found bit (may be empty)
+ * @size: The bitmap size in bits
+ * @start: The bitnumber to start searching at
+ */
+#define FIND_NEXT_BIT(FETCH, MUNGE, size, start)				\
+({										\
+	unsigned long mask, idx, tmp, sz = (size), __start = (start);		\
+										\
+	if (unlikely(__start >= sz))						\
+		goto out;							\
+										\
+	mask = MUNGE(BITMAP_FIRST_WORD_MASK(__start));				\
+	idx = __start / BITS_PER_LONG;						\
+										\
+	for (tmp = (FETCH) & mask; !tmp; tmp = (FETCH)) {			\
+		if ((idx + 1) * BITS_PER_LONG >= sz)				\
+			goto out;						\
+		idx++;								\
+	}									\
+										\
+	sz = min(idx * BITS_PER_LONG + __ffs(MUNGE(tmp)), sz);			\
+out:										\
+	sz;									\
+})
+
+#ifndef find_next_or_bit
+unsigned long _find_next_or_bit(const unsigned long *addr1, const unsigned long *addr2,
+					unsigned long nbits, unsigned long start)
+{
+	return FIND_NEXT_BIT(addr1[idx] | addr2[idx], /* nop */, nbits, start);
+}
+EXPORT_SYMBOL(_find_next_or_bit);
+#endif
+
 #ifndef find_next_zero_bit
 unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
 				 unsigned long offset)