perf/arm_cspmu: 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/20240403155950.2068109-5-dawei.li@shingroup.cn
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/drivers/perf/arm_cspmu/arm_cspmu.c b/drivers/perf/arm_cspmu/arm_cspmu.c
index b9a252272f1e9f596db7aeba99f4d28dd6b95f84..fd10042516650e651b3ba98f3404d0e7d93c0ed1 100644 (file)
--- a/drivers/perf/arm_cspmu/arm_cspmu.c
+++ b/drivers/perf/arm_cspmu/arm_cspmu.c
@@ -1322,8 +1322,7 @@ static int arm_cspmu_cpu_online(unsigned int cpu, struct hlist_node *node)
 
 static int arm_cspmu_cpu_teardown(unsigned int cpu, struct hlist_node *node)
 {
-       int dst;
-       struct cpumask online_supported;
+       unsigned int dst;
 
        struct arm_cspmu *cspmu =
                hlist_entry_safe(node, struct arm_cspmu, cpuhp_node);
@@ -1333,9 +1332,8 @@ static int arm_cspmu_cpu_teardown(unsigned int cpu, struct hlist_node *node)
                return 0;
 
        /* Choose a new CPU to migrate ownership of the PMU to */
-       cpumask_and(&online_supported, &cspmu->associated_cpus,
-                   cpu_online_mask);
-       dst = cpumask_any_but(&online_supported, cpu);
+       dst = cpumask_any_and_but(&cspmu->associated_cpus,
+                                 cpu_online_mask, cpu);
        if (dst >= nr_cpu_ids)
                return 0;