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[4.19,214/346] powerpc/pseries/hibernation: drop pseries_suspend_begin() from suspend ops

Message ID 20201228124930.124643958@linuxfoundation.org
State Superseded
Headers show
Series None | expand

Commit Message

Greg Kroah-Hartman Dec. 28, 2020, 12:48 p.m. UTC 
From: Nathan Lynch <nathanl@linux.ibm.com>

[ Upstream 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
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/powerpc/platforms/pseries/suspend.c | 1 -
 1 file changed, 1 deletion(-)
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Patch

diff --git a/arch/powerpc/platforms/pseries/suspend.c b/arch/powerpc/platforms/pseries/suspend.c
index 52a021e1f86bf..fd2c090681aa6 100644
--- a/arch/powerpc/platforms/pseries/suspend.c
+++ b/arch/powerpc/platforms/pseries/suspend.c
@@ -223,7 +223,6 @@  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,
 };