APPLIED[F]: [SRU][F][G][PATCH 0/1] smc: SMC connections hang with later-level implementations (LP: 1882088)

Kelsey Skunberg kelsey.skunberg at canonical.com
Mon Aug 3 19:20:01 UTC 2020


Applied to Focal/master-next. Thank you! 

-Kelsey

On 2020-07-10 21:21:44 , frank.heimes at canonical.com wrote:
> Buglink: https://bugs.launchpad.net/bugs/1882088
> 
> 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.
> 
> Ursula Braun (1):
>   From: Ursula Braun <ubraun at linux.ibm.com>
> 
>  net/smc/smc_clc.c | 45 ++++++++++++++++++++++++++++++++-------------
>  net/smc/smc_clc.h |  4 ++++
>  2 files changed, 36 insertions(+), 13 deletions(-)
> 
> -- 
> 2.25.1
> 
> 
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