On Mon, Oct 02, 2017 at 03:52:12PM -0700, Bart Van Assche wrote:
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 3f7426120a3b..a2cf2a93b0cb 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -8961,6 +8963,37 @@ static void md_stop_all_writes(void)
> mdelay(1000*1);
> }
>
> +/*
> + * Ensure that neither resyncing nor reshaping occurs while the system is
> + * frozen.
> + */
> +static int md_notify_pm(struct notifier_block *bl, unsigned long state,
> + void *unused)
> +{
> + struct mddev *mddev;
> + struct list_head *tmp;
> +
> + pr_debug("%s: state = %ld; system_freezing_cnt = %d\n", __func__, state,
> + atomic_read(&system_freezing_cnt));
> +
> + switch (state) {
> + case PM_HIBERNATION_PREPARE:
Hm, why not also include and use this for PM_SUSPEND_PREPARE and/or
a PM_RESTORE_PREPARE.
case PM_HIBERNATION_PREPARE:
case PM_SUSPEND_PREPARE:
case PM_RESTORE_PREPARE:
> + md_stop_all_writes();
> + break;
> + case PM_POST_HIBERNATION:
Likewise here:
case PM_POST_SUSPEND:
case PM_POST_HIBERNATION:
case PM_POST_RESTORE:
I have revised the kernel suspend ordering and indeed things issued
with the pm notifier should suffice to be processed given we actually
call the pm ops (dpm_prepare()) for device drivers *after* the notifier
is called and then after userspace is frozen. That is:
pm_suspend() --> enter_state() -->
sys_sync()
suspend_prepare() -->
__pm_notifier_call_chain(PM_SUSPEND_PREPARE, ...);
suspend_freeze_processes() -->
freeze_processes() -->
__usermodehelper_set_disable_depth(UMH_DISABLED);
freeze all tasks ...
freeze_kernel_threads()
suspend_devices_and_enter() -->
dpm_suspend_start() -->
dpm_prepare()
dpm_suspend()
suspend_enter() -->
platform_suspend_prepare()
dpm_suspend_late()
freeze_enter()
syscore_suspend()
On our way back up:
enter_state() -->
suspend_devices_and_enter() --> (bail from loop)
dpm_resume_end() -->
dpm_resume()
dpm_complete()
suspend_finish() -->
suspend_thaw_processes() -->
thaw_processes() -->
__usermodehelper_set_disable_depth(UMH_FREEZING);
thaw_workqueues();
thaw all processes ...
usermodehelper_enable();
pm_notifier_call_chain(PM_POST_SUSPEND);
So notifier would indeed be the right tooling to use here.
Luis
