[PATCH v3 2/5] cpumask: introduce cpumask_nth_and_andnot

[Yury Norov <yury.norov@gmail.com>]

Introduce cpumask_nth_and_andnot() based on find_nth_and_andnot_bit().
It's used in the following patch to traverse cpumasks without storing
intermediate result in temporary cpumask.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
 include/linux/cpumask.h | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index 9543b22d6dc2..5c4905108d1b 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -391,6 +391,26 @@ unsigned int cpumask_nth_andnot(unsigned int cpu, const struct cpumask *srcp1,
 				nr_cpumask_bits, cpumask_check(cpu));
 }
 
+/**
+ * cpumask_nth_and_andnot - get the Nth cpu set in 1st and 2nd cpumask, and clear in 3rd.
+ * @srcp1: the cpumask pointer
+ * @srcp2: the cpumask pointer
+ * @srcp3: the cpumask pointer
+ * @cpu: the N'th cpu to find, starting from 0
+ *
+ * Returns >= nr_cpu_ids if such cpu doesn't exist.
+ */
+static __always_inline
+unsigned int cpumask_nth_and_andnot(unsigned int cpu, const struct cpumask *srcp1,
+							const struct cpumask *srcp2,
+							const struct cpumask *srcp3)
+{
+	return find_nth_and_andnot_bit(cpumask_bits(srcp1),
+					cpumask_bits(srcp2),
+					cpumask_bits(srcp3),
+					nr_cpumask_bits, cpumask_check(cpu));
+}
+
 #define CPU_BITS_NONE						\
 {								\
 	[0 ... BITS_TO_LONGS(NR_CPUS)-1] = 0UL			\
-- 
2.34.1