From 4b6d1f12f9c4e0e420d5747d3ae285d8f66d627f Mon Sep 17 00:00:00 2001 From: LongX Zhang Date: Thu, 25 Oct 2012 00:21:28 +0200 Subject: driver core / PM: move the calling to device_pm_remove behind the calling to bus_remove_device We hit an hang issue when removing a mmc device on Medfield Android phone by sysfs interface. device_pm_remove will call pm_runtime_remove which would disable runtime PM of the device. After that pm_runtime_get* or pm_runtime_put* will be ignored. So if we disable the runtime PM before device really be removed, drivers' _remove callback may access HW even pm_runtime_get* fails. That is bad. Consider below call sequence when removing a device: device_del => device_pm_remove => class_intf->remove_dev(dev, class_intf) => pm_runtime_get_sync/put_sync => bus_remove_device => device_release_driver => pm_runtime_get_sync/put_sync remove_dev might call pm_runtime_get_sync/put_sync. Then, generic device_release_driver also calls pm_runtime_get_sync/put_sync. Since device_del => device_pm_remove firstly, later _get_sync wouldn't really wake up the device. I git log -p to find the patch which moves the calling to device_pm_remove ahead. It's below patch: commit 775b64d2b6ca37697de925f70799c710aab5849a Author: Rafael J. Wysocki Date: Sat Jan 12 20:40:46 2008 +0100 PM: Acquire device locks on suspend This patch reorganizes the way suspend and resume notifications are sent to drivers. The major changes are that now the PM core acquires every device semaphore before calling the methods, and calls to device_add() during suspends will fail, while calls to device_del() during suspends will block. It also provides a way to safely remove a suspended device with the help of the PM core, by using the device_pm_schedule_removal() callback introduced specifically for this purpose, and updates two drivers (msr and cpuid) that need to use it. As device_pm_schedule_removal is deleted by another patch, we need also revert other parts of the patch, i.e. move the calling of device_pm_remove after the calling to bus_remove_device. Signed-off-by: LongX Zhang Acked-by: Greg Kroah-Hartman Signed-off-by: Rafael J. Wysocki --- drivers/base/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/base/core.c') diff --git a/drivers/base/core.c b/drivers/base/core.c index abea76c36a4b..150a41580fad 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -1180,7 +1180,6 @@ void device_del(struct device *dev) if (dev->bus) blocking_notifier_call_chain(&dev->bus->p->bus_notifier, BUS_NOTIFY_DEL_DEVICE, dev); - device_pm_remove(dev); dpm_sysfs_remove(dev); if (parent) klist_del(&dev->p->knode_parent); @@ -1205,6 +1204,7 @@ void device_del(struct device *dev) device_remove_file(dev, &uevent_attr); device_remove_attrs(dev); bus_remove_device(dev); + device_pm_remove(dev); driver_deferred_probe_del(dev); /* Notify the platform of the removal, in case they -- cgit v1.2.3