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. :-) FWIW, commit 52cdbdd49853 went in during the 4.3 cycle AFAICS. Cheers, Rafael
