On Mon, Feb 17, 2020 at 10:31:56AM +0100, Niklas Schnelle wrote:
On Fri, Feb 14, 2020 at 10:41:26AM -0500, Sasha Levin wrote:From: Niklas Schnelle <schnelle@xxxxxxxxxxxxx> [ Upstream commit 576c75e36c689bec6a940e807bae27291ab0c0de ] With zpci_disable() working, lockdep detected a potential deadlock (lockdep output at the end). The deadlock is between recovering a PCI function via the /sys/bus/pci/devices/<dev>/recover attribute vs powering it off via /sys/bus/pci/slots/<slot>/power. The fix is analogous to the changes in commit 0ee223b2e1f6 ("scsi: core: Avoid that SCSI device removal through sysfs triggers a deadlock") that fixed a potential deadlock on removing a SCSI device via sysfs.[ ... snip ... ] While technically useful on its own this commit really should go together with the following upstream commit: 17cdec960cf776b20b1fb08c622221babe591d51 ("s390/pci: Recover handle in clp_set_pci_fn()") While the problem fixed here is independent, writing to the power/recover attributes will often fail due to an inconsistent function handle without the second commit. In particular without it a PCI function in the error state can not be recovered or powered off. I would recommend adding the second commit to the backports as well.
I took that commit as well, thank you. -- Thanks, Sasha
