6.12-stable review patch. If anyone has any objections, please let me know.
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From: Yaxiong Tian tianyaxiong@kylinos.cn
[ Upstream commit 179c0c7044a378198adb36f2a12410ab68cc730a ]
When the device is of a non-CPU type, table[i].performance won't be initialized in the previous em_init_performance(), resulting in division by zero when calculating costs in em_compute_costs().
Since the 'cost' algorithm is only used for EAS energy efficiency calculations and is currently not utilized by other device drivers, we should add the _is_cpu_device(dev) check to prevent this division-by-zero issue.
Fixes: 1b600da51073 ("PM: EM: Optimize em_cpu_energy() and remove division") Signed-off-by: Yaxiong Tian tianyaxiong@kylinos.cn Reviewed-by: Lukasz Luba lukasz.luba@arm.com Link: https://patch.msgid.link/tencent_7F99ED4767C1AF7889D0D8AD50F34859CE06@qq.com Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/power/energy_model.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c index 4e1778071d704..1c9fe741fe6d5 100644 --- a/kernel/power/energy_model.c +++ b/kernel/power/energy_model.c @@ -233,6 +233,10 @@ static int em_compute_costs(struct device *dev, struct em_perf_state *table, unsigned long prev_cost = ULONG_MAX; int i, ret;
+ /* This is needed only for CPUs and EAS skip other devices */ + if (!_is_cpu_device(dev)) + return 0; + /* Compute the cost of each performance state. */ for (i = nr_states - 1; i >= 0; i--) { unsigned long power_res, cost;