[PATCH 3/9] perf/arm_cspmu: Avoid explicit cpumask var allocation from stack
Dawei Li
dawei.li at shingroup.cn
Tue Apr 2 03:56:04 PDT 2024
For CONFIG_CPUMASK_OFFSTACK=y kernel, explicit allocation of cpumask
variable on stack is not recommended since it can cause potential stack
overflow.
Instead, kernel code should always use *cpumask_var API(s) to allocate
cpumask var in config- neutral way, leaving allocation strategy to
CONFIG_CPUMASK_OFFSTACK.
Use *cpumask_var API(s) to address it.
Signed-off-by: Dawei Li <dawei.li at shingroup.cn>
---
drivers/perf/arm_cspmu/arm_cspmu.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/drivers/perf/arm_cspmu/arm_cspmu.c b/drivers/perf/arm_cspmu/arm_cspmu.c
index b9a252272f1e..8fa7c26aec28 100644
--- a/drivers/perf/arm_cspmu/arm_cspmu.c
+++ b/drivers/perf/arm_cspmu/arm_cspmu.c
@@ -1322,8 +1322,8 @@ 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)
{
+ cpumask_var_t online_supported;
int dst;
- struct cpumask online_supported;
struct arm_cspmu *cspmu =
hlist_entry_safe(node, struct arm_cspmu, cpuhp_node);
@@ -1332,17 +1332,22 @@ static int arm_cspmu_cpu_teardown(unsigned int cpu, struct hlist_node *node)
if (!cpumask_test_and_clear_cpu(cpu, &cspmu->active_cpu))
return 0;
+ if (!alloc_cpumask_var(&online_supported, GFP_KERNEL))
+ return 0;
+
/* Choose a new CPU to migrate ownership of the PMU to */
- cpumask_and(&online_supported, &cspmu->associated_cpus,
+ cpumask_and(online_supported, &cspmu->associated_cpus,
cpu_online_mask);
- dst = cpumask_any_but(&online_supported, cpu);
+ dst = cpumask_any_but(online_supported, cpu);
if (dst >= nr_cpu_ids)
- return 0;
+ goto __free_cpumask;
/* Use this CPU for event counting */
perf_pmu_migrate_context(&cspmu->pmu, cpu, dst);
arm_cspmu_set_active_cpu(dst, cspmu);
+__free_cpumask:
+ free_cpumask_var(online_supported);
return 0;
}
--
2.27.0
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