[PATCH 4.9 105/175] powerpc/pseries/hibernation: drop pseries_suspend_begin() from suspend ops

Greg Kroah-Hartman
2020-12-28T16:33:44Z

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(-)

diff --git a/arch/powerpc/platforms/pseries/suspend.c b/arch/powerpc/platforms/pseries/suspend.c
index e76aefae2aa2b..0a0e0c8256f67 100644
--- a/arch/powerpc/platforms/pseries/suspend.c
+++ b/arch/powerpc/platforms/pseries/suspend.c
@@ -224,7 +224,6 @@ 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,
};
--
2.27.0