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Subject[PATCH 4/5] cpumask: add cpumask_nth_{,and,andnot}
Date
Add cpumask_nth_{,and,andnot} as wrappers around corresponding
find functions, and use it in cpumask_local_spread().

Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
include/linux/cpumask.h | 44 +++++++++++++++++++++++++++++++++++++++++
lib/cpumask.c | 26 +++++++++++-------------
2 files changed, 55 insertions(+), 15 deletions(-)

diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index 0738a6c9be40..8cf460368fca 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -379,6 +379,50 @@ unsigned int cpumask_any_but(const struct cpumask *mask, unsigned int cpu)
}
#endif /* SMP */

+/**
+ * cpumask_nth - get the first cpu in a cpumask
+ * @srcp: the cpumask pointer
+ * @cpu: the N'th cpu to find, starting from 1
+ *
+ * Returns >= nr_cpu_ids if such cpu doesn't exist.
+ */
+static inline unsigned int cpumask_nth(unsigned int cpu, const struct cpumask *srcp)
+{
+ return find_nth_bit(cpumask_bits(srcp), nr_cpumask_bits, cpumask_check(cpu));
+}
+
+/**
+ * cpumask_nth_and - get the first cpu in 2 cpumasks
+ * @srcp1: the cpumask pointer
+ * @srcp2: the cpumask pointer
+ * @cpu: the N'th cpu to find, starting from 1
+ *
+ * Returns >= nr_cpu_ids if such cpu doesn't exist.
+ */
+static inline
+unsigned int cpumask_nth_and(unsigned int cpu, const struct cpumask *srcp1,
+ const struct cpumask *srcp2)
+{
+ return find_nth_and_bit(cpumask_bits(srcp1), cpumask_bits(srcp2),
+ nr_cpumask_bits, cpumask_check(cpu));
+}
+
+/**
+ * cpumask_nth_andnot - get the first cpu set in 1st cpumask, and clear in 2nd.
+ * @srcp1: the cpumask pointer
+ * @srcp2: the cpumask pointer
+ * @cpu: the N'th cpu to find, starting from 1
+ *
+ * Returns >= nr_cpu_ids if such cpu doesn't exist.
+ */
+static inline
+unsigned int cpumask_nth_andnot(unsigned int cpu, const struct cpumask *srcp1,
+ const struct cpumask *srcp2)
+{
+ return find_nth_andnot_bit(cpumask_bits(srcp1), cpumask_bits(srcp2),
+ nr_cpumask_bits, cpumask_check(cpu));
+}
+
#define CPU_BITS_NONE \
{ \
[0 ... BITS_TO_LONGS(NR_CPUS)-1] = 0UL \
diff --git a/lib/cpumask.c b/lib/cpumask.c
index f0ae119be8c4..56aeb9c9d702 100644
--- a/lib/cpumask.c
+++ b/lib/cpumask.c
@@ -128,23 +128,19 @@ unsigned int cpumask_local_spread(unsigned int i, int node)
i %= num_online_cpus();

if (node == NUMA_NO_NODE) {
- for_each_cpu(cpu, cpu_online_mask)
- if (i-- == 0)
- return cpu;
+ cpu = cpumask_nth(i + 1, cpu_online_mask);
+ if (cpu < nr_cpu_ids)
+ return cpu;
} else {
/* NUMA first. */
- for_each_cpu_and(cpu, cpumask_of_node(node), cpu_online_mask)
- if (i-- == 0)
- return cpu;
-
- for_each_cpu(cpu, cpu_online_mask) {
- /* Skip NUMA nodes, done above. */
- if (cpumask_test_cpu(cpu, cpumask_of_node(node)))
- continue;
-
- if (i-- == 0)
- return cpu;
- }
+ cpu = cpumask_nth_and(i + 1, cpu_online_mask, cpumask_of_node(node));
+ if (cpu < nr_cpu_ids)
+ return cpu;
+
+ /* Skip NUMA nodes, done above. */
+ cpu = cpumask_nth_andnot(i + 1, cpu_online_mask, cpumask_of_node(node));
+ if (cpu < nr_cpu_ids)
+ return cpu;
}
BUG();
}
--
2.34.1
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