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PM: sleep: Simplify dpm_suspended_list walk in dpm_resume()

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Notice that devices can be moved to dpm_prepared_list before running
their resume callbacks, in analogy with dpm_noirq_resume_devices() and
dpm_resume_early(), because doing so will not affect the final ordering
of that list.

Namely, if a device is the first dpm_suspended_list entry while
dpm_list_mtx is held, it has not been removed so far and it cannot be
removed until dpm_list_mtx is released, so moving it to dpm_prepared_list
at that point is valid.  If it is removed later, while its resume
callback is running, it will be deleted from dpm_prepared_list without
changing the ordering of the other devices in that list.

Accordingly, rearrange the while () loop in dpm_resume() to move
devices to dpm_prepared_list before running their resume callbacks and
implify the locking and device reference counting in it.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
This commit is contained in:
Rafael J. Wysocki 2024-01-22 12:22:38 +01:00
parent b017500ab5
commit 86686b8f7a
1 changed files with 5 additions and 11 deletions
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16
drivers/base/power/main.c
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@ -1017,25 +1017,19 @@ void dpm_resume(pm_message_t state)
while (!list_empty(&dpm_suspended_list)) {
dev = to_device(dpm_suspended_list.next);
get_device(dev);
list_move_tail(&dev->power.entry, &dpm_prepared_list);
if (!dev->power.async_in_progress) {
get_device(dev);
mutex_unlock(&dpm_list_mtx);
device_resume(dev, state, false);
put_device(dev);
mutex_lock(&dpm_list_mtx);
}
if (!list_empty(&dev->power.entry))
list_move_tail(&dev->power.entry, &dpm_prepared_list);
mutex_unlock(&dpm_list_mtx);
put_device(dev);
mutex_lock(&dpm_list_mtx);
}
mutex_unlock(&dpm_list_mtx);
async_synchronize_full();