vhost: Add missed smp_rmb()
JIRA: https://issues.redhat.com/browse/RHEL-26104
Brew: https://brewweb.engineering.redhat.com/brew/taskinfo?taskID=60490299
Upstream Status: v6.9.rc4
Tested: No soft-lockup reported from grace-hopper05's VM in netperf test
There are two smp_rmb() missed in vhost, leading to the stale available
ring entry (head). The stale and invalid head is pushed to virtio-net
where the corresponding TxQ is marked as broken. After that, the network
stack becomes generally unavailable. Fix it by picking the upstream fixes.
df9ace7647d4 vhost: Add smp_rmb() in vhost_enable_notify()
22e1992cf7b0 vhost: Add smp_rmb() in vhost_vq_avail_empty()
Signed-off-by: Gavin Shan gshan@redhat.com
Edited by Gavin Shan