[PATCH] bus: arm-ccn: Handle correctly no-more-cpus case

Pawel Moll pawel.moll at arm.com
Thu May 14 03:50:24 PDT 2015

When migrating events the driver picks another cpu using
cpumask_any_but() function, which returns value >= nr_cpu_ids
when there is none available, not a negative value as the code
assumed. Fixed now.

Reported-by: Dan Carpenter <dan.carpenter at oracle.com>
Signed-off-by: Pawel Moll <pawel.moll at arm.com>
Another day, another arm-ccn.c update...

This time Dan's static checker spotted unsigned int target
being expected to carry negative values. Fixed now.

Interestingly enough, cpumask_any_but() implementation (and its
normal prototype) returns int, but version for NR_CPUS == 1 case,
inlined in linux/cpumask.h returns unsigned int...

 drivers/bus/arm-ccn.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/bus/arm-ccn.c b/drivers/bus/arm-ccn.c
index 7d9879e..cc322fb 100644
--- a/drivers/bus/arm-ccn.c
+++ b/drivers/bus/arm-ccn.c
@@ -1184,7 +1184,7 @@ static int arm_ccn_pmu_cpu_notifier(struct notifier_block *nb,
 		if (!cpumask_test_and_clear_cpu(cpu, &dt->cpu))
 		target = cpumask_any_but(cpu_online_mask, cpu);
-		if (target < 0)
+		if (target >= nr_cpu_ids)
 		perf_pmu_migrate_context(&dt->pmu, cpu, target);
 		cpumask_set_cpu(target, &dt->cpu);

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