The following comments (brought in at 0de8783a9): /* XXX: There's a race window where a flow covering this packet * could have already been installed since we last did the flow * lookup before upcall. This could be solved by moving the * mutex lock outside the loop, but that's an awful long time * to be locking revalidators out of making flow modifications. */
is out-dated. Back at commit 0de8783a9, the classifier is per-datapath, multiple PMDs share a same classifier. Since now we have changed into per-PMD classifier, the lookup code only prevents from the race results from megaflows installed by another non-pmd threads, through either manually calling dpctl/add-flow or handler thread installing megaflow with pmd-id == PMD_ID_NULL, there are no other threads which would insert datapath flows. Signed-off-by: Peng He <[email protected]> --- lib/dpif-netdev.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c index 70b953ae6..d92ec01fb 100644 --- a/lib/dpif-netdev.c +++ b/lib/dpif-netdev.c @@ -8403,12 +8403,11 @@ handle_packet_upcall(struct dp_netdev_pmd_thread *pmd, if (OVS_LIKELY(error != ENOSPC)) { struct dp_netdev_flow *netdev_flow; - /* XXX: There's a race window where a flow covering this packet - * could have already been installed since we last did the flow - * lookup before upcall. This could be solved by moving the - * mutex lock outside the loop, but that's an awful long time - * to be locking revalidators out of making flow modifications. */ ovs_mutex_lock(&pmd->flow_mutex); + /* Two scenarios exist where a flow could have been added while + * processing the upcall: + * 1) a flow was manually added through dpctl/add-flow. + * 2) a handler installed a flow with pmd-id == PMD_ID_NULL. */ netdev_flow = dp_netdev_pmd_lookup_flow(pmd, key, NULL); if (OVS_LIKELY(!netdev_flow)) { netdev_flow = dp_netdev_flow_add(pmd, &match, &ufid, -- 2.25.1 _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
