perf/arm-cmn: 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/20240403155950.2068109-4-dawei.li@shingroup.cn
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c
index 7ef9c7e4836b72498db6cd8d5263c2ea5bf9f730..6bfb0c4a1287ec42cbb0aa7012cee23de0181777 100644 (file)
--- a/drivers/perf/arm-cmn.c
+++ b/drivers/perf/arm-cmn.c
@@ -1950,20 +1950,20 @@ static int arm_cmn_pmu_offline_cpu(unsigned int cpu, struct hlist_node *cpuhp_no
        struct arm_cmn *cmn;
        unsigned int target;
        int node;
-       cpumask_t mask;
 
        cmn = hlist_entry_safe(cpuhp_node, struct arm_cmn, cpuhp_node);
        if (cpu != cmn->cpu)
                return 0;
 
        node = dev_to_node(cmn->dev);
-       if (cpumask_and(&mask, cpumask_of_node(node), cpu_online_mask) &&
-           cpumask_andnot(&mask, &mask, cpumask_of(cpu)))
-               target = cpumask_any(&mask);
-       else
+
+       target = cpumask_any_and_but(cpumask_of_node(node), cpu_online_mask, cpu);
+       if (target >= nr_cpu_ids)
                target = cpumask_any_but(cpu_online_mask, cpu);
+
        if (target < nr_cpu_ids)
                arm_cmn_migrate(cmn, target);
+
        return 0;
 }