[PATCH 0/1][SRU][Focal][Groovy] selftests/net: relax cpu affinity requirement in msg_zerocopy test

[Colin King]

From: Colin Ian King <colin.king at canonical.com>

BugLink: https://bugs.launchpad.net/bugs/1812620

== SRU Justification [ FOCAL ] ==

The msg_zerocopy.sh kernel self test will fail on machines that don't
have 2 or 3 CPUs such as 1 CPU cloud instances since the C test program
tries to set CPU affinity to CPUs 2 and 3 and bails out if it fails.

== Fix ==

Upstream linux-next commit

commit 16f6458f2478b55e2b628797bc81a4455045c74e
Author: Willem de Bruijn <willemb at google.com>
Date: Wed Aug 5 04:40:45 2020 -0400

    selftests/net: relax cpu affinity requirement in msg_zerocopy test

The fix now just emits a warning that CPU affinity can't be set
rather than cause an exit(1) termination.

== Test cast ==

Run the msg_zerocopy.sh test from the kernel net selftest on a 1 CPU
system or a system with CPUs 2-3 offline'd. Without the fix the test
fails. With the fix it runs successfully as expected.

== Regression Potential ==

The original test pinned the CPUs for a benchmarking metric, for our
testing we are using this to test to see if the operations in the tes
 work successfully. There is a potential that users using this test
will not notice the warning if they are using this test as a benchmark
on a 1 CPU system and may get more jittery timing in their benchmarks
rather than a test failing and complaining they are not running it on
a suitable multi-CPU system. However, the likelyhood of a user using
this test on a single CPU system for benchmarking is small and as it
stands the test will now run and produce potentially jittery benchmarks
on a 1 CPU system compared to previously where it never ran.

Willem de Bruijn (1):
  selftests/net: relax cpu affinity requirement in msg_zerocopy test

 tools/testing/selftests/net/msg_zerocopy.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

-- 
2.27.0