Messages in this thread | | | From | "Rafael J. Wysocki" <> | Date | Mon, 27 Mar 2023 19:43:02 +0200 | Subject | Re: [PATCH 3/3] PM: s2idle: Fully block the system from entering s2idle when cpuidle isn't supported |
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On Thu, Mar 16, 2023 at 8:49 AM Kazuki H <kazukih0205@gmail.com> wrote: > > s2idle isn't supported on platforms that don't support cpuidle as of > 31a3409065d1 ("cpuidle / sleep: Do sanity checks in cpuidle_enter_freeze() > too").
This simply isn't correct.
As of the above commit, s2idle was still supported without cpuidle as long as arch_cpu_idle() worked.
> There is a check in the cpuidle subsystem which would prevent the > system from entering s2idle. However, there is nothing in the suspend > framework which prevents this, which can cause the suspend subsystem to > think that the machine is entering s2idle while the cpuidle subsystem is > not, which can completely break the system. > > Block the machine from entering s2idle when cpuidle isn't supported in > the suspend subsystem as well.
First, please explain why the cpuidle_not_available() check in cpuidle_idle_call() is not sufficient to avoid the breakage.
> Link: https://lore.kernel.org/all/20230204152747.drte4uitljzngdt6@kazuki-mac > Fixes: 31a3409065d1 ("cpuidle / sleep: Do sanity checks in cpuidle_enter_freeze() too") > Signed-off-by: Kazuki H <kazukih0205@gmail.com> > --- > kernel/power/main.c | 12 +++++++++--- > kernel/power/suspend.c | 5 +++++ > 2 files changed, 14 insertions(+), 3 deletions(-) > > diff --git a/kernel/power/main.c b/kernel/power/main.c > index 31ec4a9b9d70..b14765447989 100644 > --- a/kernel/power/main.c > +++ b/kernel/power/main.c > @@ -133,6 +133,8 @@ static ssize_t mem_sleep_show(struct kobject *kobj, struct kobj_attribute *attr, > for (i = PM_SUSPEND_MIN; i < PM_SUSPEND_MAX; i++) { > if (i >= PM_SUSPEND_MEM && cxl_mem_active()) > continue; > + if (i == PM_SUSPEND_TO_IDLE && cpuidle_not_available()) > + continue;
Not really.
> if (mem_sleep_states[i]) { > const char *label = mem_sleep_states[i]; > > @@ -185,11 +187,15 @@ static ssize_t mem_sleep_store(struct kobject *kobj, struct kobj_attribute *attr > } > > state = decode_suspend_state(buf, n); > - if (state < PM_SUSPEND_MAX && state > PM_SUSPEND_ON) > + if (state == PM_SUSPEND_TO_IDLE && cpuidle_not_available())
And same here.
> + goto einval; > + if (state < PM_SUSPEND_MAX && state > PM_SUSPEND_ON) { > mem_sleep_current = state; > - else > - error = -EINVAL; > + goto out; > + } > > + einval: > + error = -EINVAL; > out: > pm_autosleep_unlock(); > return error ? error : n; > diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c > index 3f436282547c..55ddf525aaaf 100644 > --- a/kernel/power/suspend.c > +++ b/kernel/power/suspend.c > @@ -556,6 +556,11 @@ static int enter_state(suspend_state_t state) > > trace_suspend_resume(TPS("suspend_enter"), state, true); > if (state == PM_SUSPEND_TO_IDLE) { > + if (cpuidle_not_available()) { > + pr_warn("s2idle is unsupported when cpuidle is unavailable"); > + return -EINVAL; > + } > + > #ifdef CONFIG_PM_DEBUG > if (pm_test_level != TEST_NONE && pm_test_level <= TEST_CPUS) { > pr_warn("Unsupported test mode for suspend to idle, please choose none/freezer/devices/platform.\n"); > --
Again, I need to understand what the problem is in the first place.
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