[PATCH 07/17] PM: EM: Check if the get_cost() callback is present in em_compute_costs()

[Lukasz Luba]

The em_compute_cost() is going to be re-used in runtime modified EM
code path. Thus, make sure that this common code is safe and won't
try to use the NULL pointer. The former em_compute_cost() didn't have to
care about runtime modification code path. The upcoming changes introduce
such option, but with different callback. Those two paths which use
get_cost() (during first EM registration) or update_power() (during
runtime modification) need to be safely handled in em_compute_costs().

Signed-off-by: Lukasz Luba <lukasz.luba@xxxxxxx>
---
 kernel/power/energy_model.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c
index 3b778743ba89..230310709e2a 100644
--- a/kernel/power/energy_model.c
+++ b/kernel/power/energy_model.c
@@ -122,7 +122,7 @@ 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",
-- 
2.17.1