------- Comment From heinz-werner_se...@de.ibm.com 2020-09-04 03:06 EDT------- IBM Bugzilla status-> closed, Fix Released with all requested distros.
-- 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/1882088 Title: [UBUNTU 20.04] smc: SMC connections hang with later-level implementations Status in Ubuntu on IBM z Systems: Fix Released Status in linux package in Ubuntu: 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] * Connections from later-level SMC (protocol) versions to an SMC- enabled server on Linux hang. * Later-level versions of SMC (although backwards-compatible) present a higher version number and use larger messages during the CLC handshake. * The solution to avoid such hangs is to introduce toleration for later version numbers, and support CLC messages of arbitrary length. [Fix] * fb4f79264c0fc6fd5a68ffe3e31bfff97311e1f1 fb4f79264c0f "net/smc: tolerate future SMCD versions" [Test Case] * Requires two IBM z13/z13s GA2 or LinuxONE Rockhopper/Emperor systems with RoCE Express adapter v2(.1) for SMC-D usage. * One system needs to run the initial SMC-D version, the other a newer version. * Establish a connection between both system and monitor/verify if it's reliable or if it hangs. [Regression Potential] * The regression can be considered as medium to low: * Since SMC-D is a pretty special way of doing shared memory communications and not that wide-spread. * However, the code that is changed is common code. * But the patch is straight forward and only modifies /net/smc/smc_clc.c and /net/smc/smc_clc.h * It largely bumps limits (allows larger messages), adds a check and introduces toleration, rather than changing control or flow. [Other] * The above fix is currently in 'linux-next' and tagged with next-20200709. * It is still assumed that it gets accepted for 5.8. * However, since this is not guaranteed this SRU request is for focal and groovy - to make sure that no potential regressions are introduced in case the patch will not end up in 5.8. __________ Description: smc: SMC connections hang with later-level implementations Symptom: Connections from later-level SMC versions to an SMC-enabled server on Linux hang. Problem: Later-level versions of SMC present, although backwards- compatible, a higher version number, and use larger messages during the CLC handshake. Solution: Adjust for tolerating later version numbers, and support CLC messages of arbitrary length. Reproduction: Enable a server on Linux for SMC, and connect using a later- level version of SMC Applicable for: Ubuntu 20.04 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-z-systems/+bug/1882088/+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
