------- Comment From niklas.schne...@ibm.com 2020-05-20 09:09 EDT------- Verified this is working as intended. Thank you!
-- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1870320 Title: [UBUNTU 18.04] zpcictl --reset - contribution for kernel Status in Ubuntu on IBM z Systems: Fix Committed Status in linux package in Ubuntu: Fix Released Status in linux source package in Bionic: Fix Committed Status in linux source package in Eoan: Fix Released Status in linux source package in Focal: Fix Released Status in linux source package in Groovy: Fix Released Bug description: SRU Justification: ================== [Impact] * With zpci_disable() working, 'lockdep' detected a potential deadlock (in the s390x zPCI subsystem). * 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. [Fix] * Backport 1: https://launchpadlibrarian.net/479554961/0001-s390-pci- Recover-handle-in-clp_set_pci_fn.patch * Backport 2: https://launchpadlibrarian.net/478714295/0001-s390-pci- Fix-possible-deadlock-in-recover_store.patch [Test Case] * It's best to (re-)test using the kernel's locking validator, also known as 'lockdep'. * Since this potential deadlock was identified by lockdep. [Regression Potential] * The regression potential can be considered as moderate, since: * It is purely s390x specific code (arch/s390/include/asm/pci.h and arch/s390/pci/{pci.c,pci_clp.c,pci_sysfs.c}). * It only affects the zPCI, the s390x specific PCI code layer. * PCI cards available for s390x are optional cards (RoCE and zEDC) and not very wide-spread. * The states between such a deadlock can happen (recover and power off) are non standard and usually undesired states. * The patches are upstream accepted since 5.6 and already landed in eoan and focal. [Other Info] * Patches 17cdec960cf7 "s390/pci: Recover handle in clp_set_pci_fn()" and 576c75e36c68 "s390/pci: Fix possible deadlock in recover_store()" are upstream accepted since kernel 5.6, but they don't apply cleanly on bionic master-next, hence backports are needed: * 0001-s390-pci-Recover-handle-in-clp_set_pci_fn.patch is a backport of 17cdec960cf776b20b1fb08c622221babe591d51 17cdec960cf7 "s390/pci: Recover handle in clp_set_pci_fn()" * 0001-s390-pci-Fix-possible-deadlock-in-recover_store.patch is a backport of 576c75e36c689bec6a940e807bae27291ab0c0de 576c75e36c68 "s390/pci: Fix possible deadlock in recover_store()" * Both patches/commits already landed in focal (with LP 1863768) and in eoan (with LP 1868324). __________ This Bug tracks the necessary backport for the Linux Kernel to enable proper reset/recovery of PCI Functions in the error state. There is a related fix to s390-tools but the relevant zpcictl command is not part of Ubuntu 18.04 Upstream this includes the following commits: In the Kernel: 17cdec960cf776b20b1fb08c622221babe591d51 s390/pci: Recover handle in clp_set_pci_fn() Backport patch attached. 576c75e36c689bec6a940e807bae27291ab0c0de s390/pci: Fix possible deadlock in recover_store() applies cleanly but for the second a small backport change is necessary. These fixes are already in 20.04 but need also be applied to 18.04. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-z-systems/+bug/1870320/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
