This is a note to let you know that I've just added the patch titled

driver core: Partially revert "driver core: correct device's shutdown

to my driver-core git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git in the driver-core-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From 722e5f2b1eec7de61117b7c0a7914761e3da2eda Mon Sep 17 00:00:00 2001

From: "Rafael J. Wysocki" rafael.j.wysocki@intel.com Date: Tue, 10 Jul 2018 14:51:33 +0200 Subject: driver core: Partially revert "driver core: correct device's shutdown order"

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_xPAc03S... 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 Cc: stable stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/base/dd.c | 8 -------- 1 file changed, 8 deletions(-)

diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 1435d7281c66..6ebcd65d64b6 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -434,14 +434,6 @@ static int really_probe(struct device *dev, struct device_driver *drv) 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)