PM: EM: Check if the get_cost() callback is present in em_compute_costs()

Subsequent changes will introduce a case in which 'cb->get_cost' may
not be set in em_compute_costs(), so add a check to ensure that it is
not NULL before attempting to dereference it.

Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c
index 5c47caaf270e69d10a2697aca032059b73165a8d..21d76122325517af440f0d9c32f147362014cb3a 100644 (file)
--- a/kernel/power/energy_model.c
+++ b/kernel/power/energy_model.c
@@ -116,7 +116,7 @@ static int em_compute_costs(struct device *dev, struct em_perf_state *table,
        for (i = nr_states - 1; i >= 0; i--) {
                unsigned long power_res, cost;
 
-               if (flags & EM_PERF_DOMAIN_ARTIFICIAL) {
+               if ((flags & EM_PERF_DOMAIN_ARTIFICIAL) && cb->get_cost) {
                        ret = cb->get_cost(dev, table[i].frequency, &cost);
                        if (ret || !cost || cost > EM_MAX_POWER) {
                                dev_err(dev, "EM: invalid cost %lu %d\n",