perf/arm_dsu: Avoid placing cpumask on the stack

In general it's preferable to avoid placing cpumasks on the stack, as
for large values of NR_CPUS these can consume significant amounts of
stack space and make stack overflows more likely.

Use cpumask_any_and_but() to avoid the need for a temporary cpumask on
the stack.

Suggested-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Dawei Li <dawei.li@shingroup.cn>
Link: https://lore.kernel.org/r/20240403155950.2068109-6-dawei.li@shingroup.cn
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/drivers/perf/arm_dsu_pmu.c b/drivers/perf/arm_dsu_pmu.c
index bae3ca37f846ee9d7fb9c982ae3eb7d740e11ba7..adc0bbb5fafe4d6785d2f89109a16ae3844092e3 100644 (file)
--- a/drivers/perf/arm_dsu_pmu.c
+++ b/drivers/perf/arm_dsu_pmu.c
@@ -230,15 +230,6 @@ static const struct attribute_group *dsu_pmu_attr_groups[] = {
        NULL,
 };
 
-static int dsu_pmu_get_online_cpu_any_but(struct dsu_pmu *dsu_pmu, int cpu)
-{
-       struct cpumask online_supported;
-
-       cpumask_and(&online_supported,
-                        &dsu_pmu->associated_cpus, cpu_online_mask);
-       return cpumask_any_but(&online_supported, cpu);
-}
-
 static inline bool dsu_pmu_counter_valid(struct dsu_pmu *dsu_pmu, u32 idx)
 {
        return (idx < dsu_pmu->num_counters) ||
@@ -827,14 +818,16 @@ static int dsu_pmu_cpu_online(unsigned int cpu, struct hlist_node *node)
 
 static int dsu_pmu_cpu_teardown(unsigned int cpu, struct hlist_node *node)
 {
-       int dst;
-       struct dsu_pmu *dsu_pmu = hlist_entry_safe(node, struct dsu_pmu,
-                                                  cpuhp_node);
+       struct dsu_pmu *dsu_pmu;
+       unsigned int dst;
+
+       dsu_pmu = hlist_entry_safe(node, struct dsu_pmu, cpuhp_node);
 
        if (!cpumask_test_and_clear_cpu(cpu, &dsu_pmu->active_cpu))
                return 0;
 
-       dst = dsu_pmu_get_online_cpu_any_but(dsu_pmu, cpu);
+       dst = cpumask_any_and_but(&dsu_pmu->associated_cpus,
+                                 cpu_online_mask, cpu);
        /* If there are no active CPUs in the DSU, leave IRQ disabled */
        if (dst >= nr_cpu_ids)
                return 0;