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Subject[PATCH v3 04/10] perf/arm_cspmu: Avoid placing cpumask on the stack
Date
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>
---
drivers/perf/arm_cspmu/arm_cspmu.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/perf/arm_cspmu/arm_cspmu.c b/drivers/perf/arm_cspmu/arm_cspmu.c
index b9a252272f1e..fd1004251665 100644
--- 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;

--
2.27.0

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