From: Yaxiong Tian Date: Fri, 18 Apr 2025 01:06:13 +0000 (+0800) Subject: PM: EM: Fix potential division-by-zero error in em_compute_costs() X-Git-Tag: v6.16-rc1~160^2~4^2~4 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=179c0c7044a378198adb36f2a12410ab68cc730a;p=thirdparty%2Flinux.git PM: EM: Fix potential division-by-zero error in em_compute_costs() 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 Reviewed-by: Lukasz Luba Link: https://patch.msgid.link/tencent_7F99ED4767C1AF7889D0D8AD50F34859CE06@qq.com Signed-off-by: Rafael J. Wysocki --- diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c index d9b7e2b38c7a9..41606247c2776 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;