From: Wyes Karny Date: Mon, 29 May 2023 14:25:51 +0000 (+0000) Subject: cpufreq: Fail driver register if it has adjust_perf without fast_switch X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=b4a11fa3331e163e177e76098fe1d8b12b87cf6b;p=linux.git cpufreq: Fail driver register if it has adjust_perf without fast_switch If fast_switch_possible flag is set by the scaling driver, the governor is free to select fast_switch function even if adjust_perf is set. Some scaling drivers which use adjust_perf don't set fast_switch thinking that the governor would never fall back to fast_switch. But the governor can fall back to fast_switch even in runtime if frequency invariance is disabled due to some reason. This could crash the kernel if the driver didn't set the fast_switch function pointer. Therefore, fail driver registration if it has adjust_perf without fast_switch. Suggested-by: Rafael J. Wysocki Suggested-by: Viresh Kumar Signed-off-by: Wyes Karny Signed-off-by: Rafael J. Wysocki --- diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 6b52ebe5a8904..50bbc969ffe53 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -2828,7 +2828,8 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data) (driver_data->setpolicy && (driver_data->target_index || driver_data->target)) || (!driver_data->get_intermediate != !driver_data->target_intermediate) || - (!driver_data->online != !driver_data->offline)) + (!driver_data->online != !driver_data->offline) || + (driver_data->adjust_perf && !driver_data->fast_switch)) return -EINVAL; pr_debug("trying to register driver %s\n", driver_data->name); diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index 26e2eb3994841..172ff51c1b2a4 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -340,7 +340,10 @@ struct cpufreq_driver { /* * ->fast_switch() replacement for drivers that use an internal * representation of performance levels and can pass hints other than - * the target performance level to the hardware. + * the target performance level to the hardware. This can only be set + * if ->fast_switch is set too, because in those cases (under specific + * conditions) scale invariance can be disabled, which causes the + * schedutil governor to fall back to the latter. */ void (*adjust_perf)(unsigned int cpu, unsigned long min_perf,