linux-kernel - [PATCH v8 06/23] PM: EM: Check if the get_cost() callback is present in em_compute

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Message-Id: <20240208115557.1273962-7-lukasz.luba@arm.com>
Date: Thu,  8 Feb 2024 11:55:40 +0000
From: Lukasz Luba <lukasz.luba@....com>
To: linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org,
	rafael@...nel.org
Cc: lukasz.luba@....com,
	dietmar.eggemann@....com,
	rui.zhang@...el.com,
	amit.kucheria@...durent.com,
	amit.kachhap@...il.com,
	daniel.lezcano@...aro.org,
	viresh.kumar@...aro.org,
	len.brown@...el.com,
	pavel@....cz,
	mhiramat@...nel.org,
	qyousef@...alina.io,
	wvw@...gle.com,
	xuewen.yan94@...il.com
Subject: [PATCH v8 06/23] 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@....com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@....com>
Signed-off-by: Lukasz Luba <lukasz.luba@....com>
---
 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 5c47caaf270e..21d761223255 100644
--- 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",
-- 
2.25.1