3.16.40-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Brian Norris <briannorris@xxxxxxxxxxxx> 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@xxxxxxxxxxxxxx> Signed-off-by: Brian Norris <briannorris@xxxxxxxxxxxx> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> --- 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 @@ -1014,6 +1014,8 @@ static int __device_suspend_noirq(struct char *info = NULL; int error = 0; + dpm_wait_for_children(dev, async); + if (async_error) goto Complete; @@ -1025,8 +1027,6 @@ 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); @@ -1155,6 +1155,8 @@ static int __device_suspend_late(struct __pm_runtime_disable(dev, false); + dpm_wait_for_children(dev, async); + if (async_error) goto Complete; @@ -1166,8 +1168,6 @@ 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);