| Message ID | 5284251.Resgjlja2Q@aspire.rjw.lan (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
On Tue, Jul 10, 2018 at 02:51:33PM +0200, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > 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@mail.gmail.com/ > Reported-by: Pingfan Liu <kernelfans@gmail.com> > Tested-by: Pingfan Liu <kernelfans@gmail.com> > Reviewed-by: Kishon Vijay Abraham I <kishon@ti.com> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > --- > > -> 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? And shouldn't this have a stable tag as well? thanks, greg k-h
On Tue, Jul 10, 2018 at 2:59 PM, Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote: > On Tue, Jul 10, 2018 at 02:51:33PM +0200, Rafael J. Wysocki wrote: >> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> >> >> 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@mail.gmail.com/ >> Reported-by: Pingfan Liu <kernelfans@gmail.com> >> Tested-by: Pingfan Liu <kernelfans@gmail.com> >> Reviewed-by: Kishon Vijay Abraham I <kishon@ti.com> >> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> >> --- >> >> -> 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
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@linuxfoundation.org> wrote: > > On Tue, Jul 10, 2018 at 02:51:33PM +0200, Rafael J. Wysocki wrote: > >> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > >> > >> 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@mail.gmail.com/ > >> Reported-by: Pingfan Liu <kernelfans@gmail.com> > >> Tested-by: Pingfan Liu <kernelfans@gmail.com> > >> Reviewed-by: Kishon Vijay Abraham I <kishon@ti.com> > >> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > >> --- > >> > >> -> 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
Hi, On Tuesday 10 July 2018 09:17 PM, Greg Kroah-Hartman wrote: > 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@linuxfoundation.org> wrote: >>> On Tue, Jul 10, 2018 at 02:51:33PM +0200, Rafael J. Wysocki wrote: >>>> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> >>>> >>>> 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@mail.gmail.com/ >>>> Reported-by: Pingfan Liu <kernelfans@gmail.com> >>>> Tested-by: Pingfan Liu <kernelfans@gmail.com> >>>> Reviewed-by: Kishon Vijay Abraham I <kishon@ti.com> >>>> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> >>>> --- >>>> >>>> -> 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. sure. If I see the issue in dra7, I'll send a stable fix in omap_hsmmmc driver. Thanks Kishon
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)