[ovs-dev] [PATCH] Revert "odp-util: Always report ODP_FIT_TOO_LITTLE for IGMP."

Ilya Maximets i.maximets at ovn.org
Thu Nov 4 13:10:39 UTC 2021


On 11/1/21 15:47, Aaron Conole wrote:
> This reverts commit c645550bb249 ("odp-util: Always report 
> ODP_FIT_TOO_LITTLE for IGMP.")
> 
> Always forcing a slow path action can result in some over-broad
> flows which swallow all traffic and force them to userspace, as reported
> in the thread at
> https://mail.openvswitch.org/pipermail/ovs-dev/2021-September/387706.html
> and at
> https://mail.openvswitch.org/pipermail/ovs-dev/2021-September/387689.html

Hey, Aaron.  Thanks for the patch!

I think, we need to have unit tests for described issues included in
this patch.  This over-board match seems to be a serious issue and
we need to be sure that it's really fixed and will not happen again.

> 
> Revert the ODP_FIT_TOO_LITTLE return for IGMP specifically.
> Additionally, remove the userspace wc mask to prevent revalidator from
> cycling flows.

This also looks like a good candidate for a unit test as we need to
be sure that we're not re-introducing the issue that the original commit
tried to fix.

Best regards, Ilya Maximets.

> 
> Fixes: c645550bb249 ("odp-util: Always report ODP_FIT_TOO_LITTLE for IGMP.")
> Signed-off-by: Aaron Conole <aconole at redhat.com>
> ---
>  lib/odp-util.c               | 5 -----
>  ofproto/ofproto-dpif-xlate.c | 1 -
>  2 files changed, 6 deletions(-)
> 
> diff --git a/lib/odp-util.c b/lib/odp-util.c
> index fbdfc7ad83..0f21ffe639 100644
> --- a/lib/odp-util.c
> +++ b/lib/odp-util.c
> @@ -7132,11 +7132,6 @@ parse_l2_5_onward(const struct nlattr *attrs[OVS_KEY_ATTR_MAX + 1],
>                  }
>              }
>          }
> -    } else if (src_flow->nw_proto == IPPROTO_IGMP
> -               && src_flow->dl_type == htons(ETH_TYPE_IP)) {
> -        /* OVS userspace parses the IGMP type, code, and group, but its
> -         * datapaths do not, so there is always missing information. */
> -        return ODP_FIT_TOO_LITTLE;
>      }
>      if (is_mask && expected_bit != OVS_KEY_ATTR_UNSPEC) {
>          if ((flow->tp_src || flow->tp_dst) && flow->nw_proto != 0xff) {
> diff --git a/ofproto/ofproto-dpif-xlate.c b/ofproto/ofproto-dpif-xlate.c
> index 9d336bc6a6..3a0c610276 100644
> --- a/ofproto/ofproto-dpif-xlate.c
> +++ b/ofproto/ofproto-dpif-xlate.c
> @@ -3048,7 +3048,6 @@ xlate_normal(struct xlate_ctx *ctx)
>               */
>              ctx->xout->slow |= SLOW_ACTION;
>  
> -            memset(&wc->masks.tp_src, 0xff, sizeof wc->masks.tp_src);
>              if (mcast_snooping_is_membership(flow->tp_src) ||
>                  mcast_snooping_is_query(flow->tp_src)) {
>                  if (ctx->xin->allow_side_effects && ctx->xin->packet) {
> 



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