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 <asutoshd@codeaurora.org>
Fixes: 4c06c4e6cf ("driver core: Fix possible supplier PM-usage counter imbalance")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: 5.1+ <stable@vger.kernel.org> # 5.1+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
9dfacc54a8