From 52719fce3f4c7a8ac9eaa191e8d75a697f9fbcbc Mon Sep 17 00:00:00 2001

From: Nathan Lynch <nathanl@linux.ibm.com>

Date: Mon, 7 Dec 2020 15:51:49 -0600

Subject: [PATCH] powerpc/pseries/hibernation: drop pseries_suspend_begin()

 from suspend ops

References: bsc#1181674 ltc#189159

Patch-mainline: v5.11-rc1

Git-commit: 52719fce3f4c7a8ac9eaa191e8d75a697f9fbcbc

There are three ways pseries_suspend_begin() can be reached:

1. When "mem" is written to /sys/power/state:

kobj_attr_store()

-> state_store()

  -> pm_suspend()

    -> suspend_devices_and_enter()

      -> pseries_suspend_begin()

This never works because there is no way to supply a valid stream id

using this interface, and H_VASI_STATE is called with a stream id of

zero. So this call path is useless at best.

2. When a stream id is written to /sys/devices/system/power/hibernate.

pseries_suspend_begin() is polled directly from store_hibernate()

until the stream is in the "Suspending" state (i.e. the platform is

ready for the OS to suspend execution):

dev_attr_store()

-> store_hibernate()

  -> pseries_suspend_begin()

3. When a stream id is written to /sys/devices/system/power/hibernate

(continued). After #2, pseries_suspend_begin() is called once again

from the pm core:

dev_attr_store()

-> store_hibernate()

  -> pm_suspend()

    -> suspend_devices_and_enter()

      -> pseries_suspend_begin()

This is redundant because the VASI suspend state is already known to

be Suspending.

The begin() callback of platform_suspend_ops is optional, so we can

simply remove that assignment with no loss of function.

Fixes: 32d8ad4e621d ("powerpc/pseries: Partition hibernation support")

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Link: https://lore.kernel.org/r/20201207215200.1785968-18-nathanl@linux.ibm.com

Acked-by: Michal Suchanek <msuchanek@suse.de>

---

 arch/powerpc/platforms/pseries/suspend.c | 1 -

 1 file changed, 1 deletion(-)

diff --git a/arch/powerpc/platforms/pseries/suspend.c b/arch/powerpc/platforms/pseries/suspend.c

index 81e0ac58d620..3eaa9d59dc7a 100644

--- a/arch/powerpc/platforms/pseries/suspend.c

+++ b/arch/powerpc/platforms/pseries/suspend.c

@@ -187,7 +187,6 @@ static struct bus_type suspend_subsys = {

 static const struct platform_suspend_ops pseries_suspend_ops = {

 	.valid		= suspend_valid_only_mem,

-	.begin		= pseries_suspend_begin,

 	.prepare_late	= pseries_prepare_late,

 	.enter		= pseries_suspend_enter,

 };

-- 

2.26.2