On Fri, Jul 6, 2018 at 5:01 AM Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote: > > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > > The devices_kset_move_last() call in really_probe() is a mistake > as it may cause parents to follow children in the devices_kset list > which then causes system shutdown to fail. Namely, if a device has > children before really_probe() is called for it (which is not > uncommon), that call will cause it to be reordered after the children > in the devices_kset list and the ordering of that list will not > reflect the correct device shutdown order. > > Also it causes the devices_kset list to be constantly reordered > until all drivers have been probed which is totally pointless > overhead in the majority of cases. > > For that reason, revert the really_probe() modifications made by > commit 52cdbdd49853. I'm sure you've considered this, but I can't figure out whether this patch will reintroduce the problem that was solved by 52cdbdd49853. That patch updated two places: (1) really_probe(), the change you're reverting here, and (2) device_move(). device_move() is only called from 4-5 places, none of which look related to the problem fixed by 52cdbdd49853, so it seems like that problem was probably resolved by the hunk you're reverting. > Fixes: 52cdbdd49853 (driver core: correct device's shutdown order) > Link: https://lore.kernel.org/lkml/CAFgQCTt7VfqM=UyCnvNFxrSw8Z6cUtAi3HUwR4_xPAc03SgHjQ@xxxxxxxxxxxxxx/ > Reported-by: Pingfan Liu <kernelfans@xxxxxxxxx> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > --- > drivers/base/dd.c | 8 -------- > 1 file changed, 8 deletions(-) > > Index: linux-pm/drivers/base/dd.c > =================================================================== > --- linux-pm.orig/drivers/base/dd.c > +++ linux-pm/drivers/base/dd.c > @@ -434,14 +434,6 @@ re_probe: > goto probe_failed; > } > > - /* > - * Ensure devices are listed in devices_kset in correct order > - * It's important to move Dev to the end of devices_kset before > - * calling .probe, because it could be recursive and parent Dev > - * should always go first > - */ > - devices_kset_move_last(dev); > - > if (dev->bus->probe) { > ret = dev->bus->probe(dev); > if (ret) >
