Date:   Thu, 30 Jun 2022 01:02:33 +0200
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     Kalesh Singh <kaleshsingh@...gle.com>
Cc:     Christoph Hellwig <hch@....de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Arve Hjønnevåg <arve@...roid.com>,
        Todd Kjos <tkjos@...roid.com>,
        Martijn Coenen <maco@...roid.com>,
        Joel Fernandes <joel@...lfernandes.org>,
        Christian Brauner <brauner@...nel.org>,
        Hridya Valsaraju <hridya@...gle.com>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Theodore Ts'o <tytso@....edu>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        "Alex Xu (Hello71)" <alex_y_xu@...oo.ca>,
        Paolo Abeni <pabeni@...hat.com>, Rob Herring <robh@...nel.org>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Frederic Weisbecker <frederic@...nel.org>,
        Neeraj Upadhyay <quic_neeraju@...cinc.com>,
        Josh Triplett <josh@...htriplett.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        Shuah Khan <shuah@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>, wireguard@...ts.zx2c4.com,
        netdev@...r.kernel.org, rcu <rcu@...r.kernel.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@...r.kernel.org>, sultan@...neltoast.com,
        android-kernel-team <android-kernel-team@...gle.com>,
        John Stultz <jstultz@...gle.com>,
        Saravana Kannan <saravanak@...gle.com>, rafael@...nel.org
Subject: Re: [PATCH] remove CONFIG_ANDROID

Hi Kalesh,

On Wed, Jun 29, 2022 at 03:26:33PM -0700, Kalesh Singh wrote:
> Thanks for taking a look. I'm concerned holding the sys/power/state
> open would have unintentional side effects. Adding the
> /sys/power/userspace_autosuspender seems more appropriate. We don't
> have a use case for the refcounting, so would prefer the simpler
> writing '0' / '1' to toggle semantics.

Alright. So I've cooked you up some code that you can submit, since I
assume based on Christoph's bristliness that he won't do so. The below
adds /sys/power/pm_userspace_autosleeper, which you can write a 0 or a 1
into, and fixes up wireguard and random.c to use it. The code is
untested, but should generally be the correct thing, I think.

So in order of operations:

1. You write a patch for SystemSuspend.cpp and post it on Gerrit.

2. You take the diff below, clean it up or bikeshed the naming a bit or
   do whatever there, and submit it to Rafael's PM tree, including as a
   `Link: ...` this thread and the Gerrit link.

3. When/if Rafael accepts the patch, you submit the Gerrit CL.

4. When both have landed, Christoph moves forward with his
   CONFIG_ANDROID removal.

Does that seem like a reasonable way forward?

Jason

diff --git a/drivers/char/random.c b/drivers/char/random.c
index e3dd1dd3dd22..c25e3be10d9c 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -756,7 +756,7 @@ static int random_pm_notification(struct notifier_block *nb, unsigned long actio
 
 	if (crng_ready() && (action == PM_RESTORE_PREPARE ||
 	    (action == PM_POST_SUSPEND &&
-	     !IS_ENABLED(CONFIG_PM_AUTOSLEEP) && !IS_ENABLED(CONFIG_ANDROID)))) {
+	     !IS_ENABLED(CONFIG_PM_AUTOSLEEP) && !pm_userspace_autosleeper_enabled))) {
 		crng_reseed();
 		pr_notice("crng reseeded on system resumption\n");
 	}
diff --git a/drivers/net/wireguard/device.c b/drivers/net/wireguard/device.c
index aa9a7a5970fd..1983e0fadb6e 100644
--- a/drivers/net/wireguard/device.c
+++ b/drivers/net/wireguard/device.c
@@ -69,7 +69,7 @@ static int wg_pm_notification(struct notifier_block *nb, unsigned long action, v
 	 * its normal operation rather than as a somewhat rare event, then we
 	 * don't actually want to clear keys.
 	 */
-	if (IS_ENABLED(CONFIG_PM_AUTOSLEEP) || IS_ENABLED(CONFIG_ANDROID))
+	if (IS_ENABLED(CONFIG_PM_AUTOSLEEP) || pm_userspace_autosleeper_enabled)
 		return 0;
 
 	if (action != PM_HIBERNATION_PREPARE && action != PM_SUSPEND_PREPARE)
diff --git a/include/linux/suspend.h b/include/linux/suspend.h
index 70f2921e2e70..0acff26f87b4 100644
--- a/include/linux/suspend.h
+++ b/include/linux/suspend.h
@@ -498,6 +498,7 @@ extern void ksys_sync_helper(void);
 /* drivers/base/power/wakeup.c */
 extern bool events_check_enabled;
 extern suspend_state_t pm_suspend_target_state;
+extern bool pm_userspace_autosleeper_enabled;
 
 extern bool pm_wakeup_pending(void);
 extern void pm_system_wakeup(void);
@@ -537,6 +538,8 @@ static inline void pm_system_irq_wakeup(unsigned int irq_number) {}
 static inline void lock_system_sleep(void) {}
 static inline void unlock_system_sleep(void) {}
 
+#define pm_userspace_autosleeper_enabled (false)
+
 #endif /* !CONFIG_PM_SLEEP */
 
 #ifdef CONFIG_PM_SLEEP_DEBUG
diff --git a/kernel/power/main.c b/kernel/power/main.c
index e3694034b753..08f32a281010 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -120,6 +120,23 @@ static ssize_t pm_async_store(struct kobject *kobj, struct kobj_attribute *attr,
 
 power_attr(pm_async);
 
+bool pm_userspace_autosleeper_enabled;
+
+static ssize_t pm_userspace_autosleeper_show(struct kobject *kobj,
+				struct kobj_attribute *attr, char *buf)
+{
+	return sprintf(buf, "%d\n", pm_userspace_autosleeper_enabled);
+}
+
+static ssize_t pm_userspace_autosleeper_store(struct kobject *kobj,
+				    struct kobj_attribute *attr,
+				    const char *buf, size_t n)
+{
+	return kstrtobool(buf, &pm_userspace_autosleeper_enabled);
+}
+
+power_attr(pm_userspace_autosleeper);
+
 #ifdef CONFIG_SUSPEND
 static ssize_t mem_sleep_show(struct kobject *kobj, struct kobj_attribute *attr,
 			      char *buf)
@@ -869,6 +886,7 @@ static struct attribute * g[] = {
 #ifdef CONFIG_PM_SLEEP
 	&pm_async_attr.attr,
 	&wakeup_count_attr.attr,
+	&pm_userspace_autosleeper.attr,
 #ifdef CONFIG_SUSPEND
 	&mem_sleep_attr.attr,
 	&sync_on_suspend_attr.attr,

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