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| author | Yaxiong Tian <tianyaxiong@kylinos.cn> | 2025-04-18 04:06:13 +0300 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2025-04-28 16:28:59 +0300 |
| commit | 179c0c7044a378198adb36f2a12410ab68cc730a (patch) | |
| tree | 58f29002ae799e16a13e06016a7f44baae013de2 | |
| parent | b4432656b36e5cc1d50a1f2dc15357543add530e (diff) | |
| download | linux-179c0c7044a378198adb36f2a12410ab68cc730a.tar.xz | |
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 <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>
| -rw-r--r-- | kernel/power/energy_model.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c index d9b7e2b38c7a..41606247c277 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; |