lkml.org 
[lkml]   [2016]   [Nov]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 4.8 48/67] PM / sleep: dont suspend parent when async child suspend_{noirq, late} fails
Date
4.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Brian Norris <briannorris@chromium.org>

commit 6f75c3fd56daf547d684127a7f83c283c3c160d1 upstream.

Consider two devices, A and B, where B is a child of A, and B utilizes
asynchronous suspend (it does not matter whether A is sync or async). If
B fails to suspend_noirq() or suspend_late(), or is interrupted by a
wakeup (pm_wakeup_pending()), then it aborts and sets the async_error
variable. However, device A does not (immediately) check the async_error
variable; it may continue to run its own suspend_noirq()/suspend_late()
callback. This is bad.

We can resolve this problem by doing our error and wakeup checking
(particularly, for the async_error flag) after waiting for children to
suspend, instead of before. This also helps align the logic for the noirq and
late suspend cases with the logic in __device_suspend().

It's easy to observe this erroneous behavior by, for example, forcing a
device to sleep a bit in its suspend_noirq() (to ensure the parent is
waiting for the child to complete), then return an error, and watch the
parent suspend_noirq() still get called. (Or similarly, fake a wakeup
event at the right (or is it wrong?) time.)

Fixes: de377b397272 (PM / sleep: Asynchronous threads for suspend_late)
Fixes: 28b6fd6e3779 (PM / sleep: Asynchronous threads for suspend_noirq)
Reported-by: Jeffy Chen <jeffy.chen@rock-chips.com>
Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/base/power/main.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -1027,6 +1027,8 @@ static int __device_suspend_noirq(struct
TRACE_DEVICE(dev);
TRACE_SUSPEND(0);

+ dpm_wait_for_children(dev, async);
+
if (async_error)
goto Complete;

@@ -1038,8 +1040,6 @@ static int __device_suspend_noirq(struct
if (dev->power.syscore || dev->power.direct_complete)
goto Complete;

- dpm_wait_for_children(dev, async);
-
if (dev->pm_domain) {
info = "noirq power domain ";
callback = pm_noirq_op(&dev->pm_domain->ops, state);
@@ -1174,6 +1174,8 @@ static int __device_suspend_late(struct

__pm_runtime_disable(dev, false);

+ dpm_wait_for_children(dev, async);
+
if (async_error)
goto Complete;

@@ -1185,8 +1187,6 @@ static int __device_suspend_late(struct
if (dev->power.syscore || dev->power.direct_complete)
goto Complete;

- dpm_wait_for_children(dev, async);
-
if (dev->pm_domain) {
info = "late power domain ";
callback = pm_late_early_op(&dev->pm_domain->ops, state);

\
 
 \ /
  Last update: 2016-11-24 16:41    [W:0.316 / U:0.860 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site