linux-stable.git/drivers/base/power/runtime.c, branch v5.13.2

PM: runtime: Fix unpaired parent child_count for force_resume

2021-05-10T17:14:01+00:00

As pm_runtime_need_not_resume() relies also on usage_count, it can return
a different value in pm_runtime_force_suspend() compared to when called in
pm_runtime_force_resume(). Different return values can happen if anything
calls PM runtime functions in between, and causes the parent child_count
to increase on every resume.

So far I've seen the issue only for omapdrm that does complicated things
with PM runtime calls during system suspend for legacy reasons:

omap_atomic_commit_tail() for omapdrm.0
 dispc_runtime_get()
  wakes up 58000000.dss as it's the dispc parent
   dispc_runtime_resume()
    rpm_resume() increases parent child_count
 dispc_runtime_put() won't idle, PM runtime suspend blocked
pm_runtime_force_suspend() for 58000000.dss, !pm_runtime_need_not_resume()
 __update_runtime_status()
system suspended
pm_runtime_force_resume() for 58000000.dss, pm_runtime_need_not_resume()
 pm_runtime_enable() only called because of pm_runtime_need_not_resume()
omap_atomic_commit_tail() for omapdrm.0
 dispc_runtime_get()
  wakes up 58000000.dss as it's the dispc parent
   dispc_runtime_resume()
    rpm_resume() increases parent child_count
 dispc_runtime_put() won't idle, PM runtime suspend blocked
...
rpm_suspend for 58000000.dss but parent child_count is now unbalanced

Let's fix the issue by adding a flag for needs_force_resume and use it in
pm_runtime_force_resume() instead of pm_runtime_need_not_resume().

Additionally omapdrm system suspend could be simplified later on to avoid
lots of unnecessary PM runtime calls and the complexity it adds. The
driver can just use internal functions that are shared between the PM
runtime and system suspend related functions.

Fixes: 4918e1f87c5f ("PM / runtime: Rework pm_runtime_force_suspend/resume()")
Signed-off-by: Tony Lindgren 
Reviewed-by: Ulf Hansson 
Tested-by: Tomi Valkeinen 
Cc: 4.16+  # 4.16+
Signed-off-by: Rafael J. Wysocki

PM: runtime: remove kernel-doc warnings

2021-04-07T17:21:09+00:00

remove make W=1 warnings

drivers/base/power/runtime.c:926: warning: Function parameter or
member 'timer' not described in 'pm_suspend_timer_fn'

drivers/base/power/runtime.c:926: warning: Excess function parameter
'data' description in 'pm_suspend_timer_fn'

Signed-off-by: Pierre-Louis Bossart 
Signed-off-by: Rafael J. Wysocki

PM: runtime: Fix race getting/putting suppliers at probe

2021-03-29T17:27:09+00:00

pm_runtime_put_suppliers() must not decrement rpm_active unless the
consumer is suspended. That is because, otherwise, it could suspend
suppliers for an active consumer.

That can happen as follows:

 static int driver_probe_device(struct device_driver *drv, struct device *dev)
 {
	int ret = 0;

	if (!device_is_registered(dev))
		return -ENODEV;

	dev->can_match = true;
	pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
		 drv->bus->name, __func__, dev_name(dev), drv->name);

	pm_runtime_get_suppliers(dev);
	if (dev->parent)
		pm_runtime_get_sync(dev->parent);

 At this point, dev can runtime suspend so rpm_put_suppliers() can run,
 rpm_active becomes 1 (the lowest value).

	pm_runtime_barrier(dev);
	if (initcall_debug)
		ret = really_probe_debug(dev, drv);
	else
		ret = really_probe(dev, drv);

 Probe callback can have runtime resumed dev, and then runtime put
 so dev is awaiting autosuspend, but rpm_active is 2.

	pm_request_idle(dev);

	if (dev->parent)
		pm_runtime_put(dev->parent);

	pm_runtime_put_suppliers(dev);

 Now pm_runtime_put_suppliers() will put the supplier
 i.e. rpm_active 2 -> 1, but consumer can still be active.

	return ret;
 }

Fix by checking the runtime status. For any status other than
RPM_SUSPENDED, rpm_active can be considered to be "owned" by
rpm_[get/put]_suppliers() and pm_runtime_put_suppliers() need do nothing.

Reported-by: Asutosh Das 
Fixes: 4c06c4e6cf63 ("driver core: Fix possible supplier PM-usage counter imbalance")
Signed-off-by: Adrian Hunter 
Cc: 5.1+  # 5.1+
Signed-off-by: Rafael J. Wysocki

PM: runtime: Fix ordering in pm_runtime_get_suppliers()

2021-03-29T17:27:09+00:00

rpm_active indicates how many times the supplier usage_count has been
incremented. Consequently it must be updated after pm_runtime_get_sync() of
the supplier, not before.

Fixes: 4c06c4e6cf63 ("driver core: Fix possible supplier PM-usage counter imbalance")
Signed-off-by: Adrian Hunter 
Cc: 5.1+  # 5.1+
Signed-off-by: Rafael J. Wysocki

PM: runtime: Defer suspending suppliers

2021-03-22T14:21:38+00:00

Because the PM-runtime status of the device is not updated in
__rpm_callback(), attempts to suspend the suppliers of the given
device triggered by the rpm_put_suppliers() call in there may
cause a supplier to be suspended completely before the status of
the consumer is updated to RPM_SUSPENDED, which is confusing.

To avoid that (1) modify __rpm_callback() to only decrease the
PM-runtime usage counter of each supplier and (2) make rpm_suspend()
try to suspend the suppliers after changing the consumer's status to
RPM_SUSPENDED, in analogy with the device's parent.

Link: https://lore.kernel.org/linux-pm/CAPDyKFqm06KDw_p8WXsM4dijDbho4bb6T4k50UqqvR1_COsp8g@mail.gmail.com/
Fixes: 21d5c57b3726 ("PM / runtime: Use device links")
Reported-by: elaine.zhang 
Diagnosed-by: Ulf Hansson 
Reviewed-by: Ulf Hansson 
Signed-off-by: Rafael J. Wysocki

Revert "PM: runtime: Update device status before letting suppliers suspend"

2021-03-19T15:35:47+00:00

Revert commit 44cc89f76464 ("PM: runtime: Update device status
before letting suppliers suspend") that introduced a race condition
into __rpm_callback() which allowed a concurrent rpm_resume() to
run and resume the device prematurely after its status had been
changed to RPM_SUSPENDED by __rpm_callback().

Fixes: 44cc89f76464 ("PM: runtime: Update device status before letting suppliers suspend")
Link: https://lore.kernel.org/linux-pm/24dfb6fc-5d54-6ee2-9195-26428b7ecf8a@intel.com/
Reported-by: Adrian Hunter 
Cc: 4.10+  # 4.10+
Signed-off-by: Rafael J. Wysocki 
Reviewed-by: Ulf Hansson

PM: runtime: Update device status before letting suppliers suspend

2021-03-01T16:40:38+00:00

Because the PM-runtime status of the device is not updated in
__rpm_callback(), attempts to suspend the suppliers of the given
device triggered by rpm_put_suppliers() called by it may fail.

Fix this by making __rpm_callback() update the device's status to
RPM_SUSPENDED before calling rpm_put_suppliers() if the current
status of the device is RPM_SUSPENDING and the callback just invoked
by it has returned 0 (success).

While at it, modify the code in __rpm_callback() to always check
the device's PM-runtime status under its PM lock.

Link: https://lore.kernel.org/linux-pm/CAPDyKFqm06KDw_p8WXsM4dijDbho4bb6T4k50UqqvR1_COsp8g@mail.gmail.com/
Fixes: 21d5c57b3726 ("PM / runtime: Use device links")
Reported-by: Elaine Zhang 
Diagnosed-by: Ulf Hansson 
Signed-off-by: Rafael J. Wysocki 
Tested-by: Elaine Zhang 
Reviewed-by: Ulf Hansson 
Cc: 4.10+  # 4.10+
Signed-off-by: Rafael J. Wysocki

PM: runtime: Fix resposible -> responsible in runtime.c

2021-01-22T15:51:15+00:00

s/resposible/responsible/

Signed-off-by: Bhaskar Chowdhury 
Acked-by: Randy Dunlap 
[ rjw: Subject edit ]
Signed-off-by: Rafael J. Wysocki

PM: runtime: Drop pm_runtime_clean_up_links()

2020-11-02T17:14:07+00:00

After commit d12544fb2aa9 ("PM: runtime: Remove link state checks in
rpm_get/put_supplier()") nothing prevents the consumer device's
runtime PM from acquiring additional references to the supplier
device after pm_runtime_clean_up_links() has run (or even while it
is running), so calling this function from __device_release_driver()
may be pointless (or even harmful).

Moreover, it ignores stateless device links, so the runtime PM
handling of managed and stateless device links is inconsistent
because of it, so better get rid of it entirely.

Fixes: d12544fb2aa9 ("PM: runtime: Remove link state checks in rpm_get/put_supplier()")
Signed-off-by: Rafael J. Wysocki 
Cc: 5.1+  # 5.1+
Tested-by: Xiang Chen 
Reviewed-by: Greg Kroah-Hartman

PM: runtime: Drop runtime PM references to supplier on link removal

2020-11-02T17:14:07+00:00

While removing a device link, drop the supplier device's runtime PM
usage counter as many times as needed to drop all of the runtime PM
references to it from the consumer in addition to dropping the
consumer's link count.

Fixes: baa8809f6097 ("PM / runtime: Optimize the use of device links")
Signed-off-by: Rafael J. Wysocki 
Cc: 5.1+  # 5.1+
Tested-by: Xiang Chen 
Reviewed-by: Greg Kroah-Hartman