On Tue, Jul 10, 2018 at 05:40:21PM +0200, Rafael J. Wysocki wrote: > On Tue, Jul 10, 2018 at 2:59 PM, Greg Kroah-Hartman > <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > On Tue, Jul 10, 2018 at 02:51:33PM +0200, Rafael J. Wysocki wrote: > >> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > >> > >> Commit 52cdbdd49853 (driver core: correct device's shutdown order) > >> introduced a regression by breaking device shutdown on some systems. > >> > >> Namely, the devices_kset_move_last() call in really_probe() added by > >> that commit is a mistake as it may cause parents to follow children > >> in the devices_kset list which then causes shutdown to fail. For > >> example, 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 any more. > >> > >> 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 and it only covered an issue > >> with system shutdown, while system-wide suspend/resume potentially > >> had the same issue on the affected platforms (which was not covered). > >> > >> Moreover, the shutdown issue originally addressed by the change in > >> really_probe() made by commit 52cdbdd49853 is not present in 4.18-rc > >> any more, since dra7 started to use the sdhci-omap driver which > >> doesn't disable any regulators during shutdown, so the really_probe() > >> part of commit 52cdbdd49853 can be safely reverted. [The original > >> issue was related to the omap_hsmmc driver used by dra7 previously.] > >> > >> For the above reasons, revert the really_probe() modifications made > >> by commit 52cdbdd49853. > >> > >> The other code changes made by commit 52cdbdd49853 are useful and > >> they need not be reverted. > >> > >> 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> > >> Tested-by: Pingfan Liu <kernelfans@xxxxxxxxx> > >> Reviewed-by: Kishon Vijay Abraham I <kishon@xxxxxx> > >> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > >> --- > >> > >> -> v2: Added information from Kishon on the fact that it should be safe > >> to revert the really_probe() modifications added by the > >> problematic commit. Also added the Reviewed-by tag from Kishon. > > > > Looks good to me, want me to queue it up in my tree, or are you going to > > send it on to Linus? > > Please queue it up. > > > And shouldn't this have a stable tag as well? > > That is sort of a gray area, because I think it may expose the > shutdown issue on dra7 in -stable, but technically it still fixes a > regression in the driver core. So your call I suppose. :-) Being bug compatible is key :) I'll add a stable tag. thanks, greg k-h
