Looks good to me, thanks. Reviewed-by: Yifeng Sun <[email protected]>
On Mon, Aug 20, 2018 at 8:26 PM Ben Pfaff <[email protected]> wrote: > Until now, OVS did multicast snooping outputs holding the read-lock on > the mcast_snooping object. This could recurse via a patch port to try to > take the write-lock on the same object, which deadlocked. This patch fixes > the problem, by releasing the read-lock before doing any outputs. > > It would probably be better to use RCU for mcast_snooping. That would be > a bigger patch and less suitable for backporting. > > Reported-by: Sameh Elsharkawy > Reported-at: https://github.com/openvswitch/ovs-issues/issues/153 > Signed-off-by > <https://github.com/openvswitch/ovs-issues/issues/153Signed-off-by>: Ben > Pfaff <[email protected]> > --- > ofproto/ofproto-dpif-xlate.c | 102 > +++++++++++++++++++++++++++++++++++-------- > 1 file changed, 84 insertions(+), 18 deletions(-) > > diff --git a/ofproto/ofproto-dpif-xlate.c b/ofproto/ofproto-dpif-xlate.c > index e26f6c8f554a..7701b64a2451 100644 > --- a/ofproto/ofproto-dpif-xlate.c > +++ b/ofproto/ofproto-dpif-xlate.c > @@ -534,6 +534,8 @@ static void do_xlate_actions(const struct ofpact *, > size_t ofpacts_len, > static void clone_xlate_actions(const struct ofpact *, size_t ofpacts_len, > struct xlate_ctx *, bool, bool); > static void xlate_normal(struct xlate_ctx *); > +static void xlate_normal_flood(struct xlate_ctx *ct, > + struct xbundle *in_xbundle, struct xvlan > *); > static void xlate_table_action(struct xlate_ctx *, ofp_port_t in_port, > uint8_t table_id, bool may_packet_in, > bool honor_table_miss, bool with_ct_orig, > @@ -2690,6 +2692,53 @@ update_mcast_snooping_table(const struct xlate_ctx > *ctx, > } > ovs_rwlock_unlock(&ms->rwlock); > } > + > +/* A list of multicast output ports. > + * > + * We accumulate output ports and then do all the outputs afterward. It > would > + * be more natural to do the outputs one at a time as we discover the > need for > + * each one, but this can cause a deadlock because we need to take the > + * mcast_snooping's rwlock for reading to iterate through the port lists > and > + * doing an output, if it goes to a patch port, can eventually come back > to the > + * same mcast_snooping and attempt to take the write lock (see > + * https://github.com/openvswitch/ovs-issues/issues/153). */ > +struct mcast_output { > + /* Discrete ports. */ > + struct xbundle **xbundles; > + size_t n, allocated; > + > + /* If set, flood to all ports. */ > + bool flood; > +}; > +#define MCAST_OUTPUT_INIT { NULL, 0, 0, false } > + > +/* Add 'mcast_bundle' to 'out'. */ > +static void > +mcast_output_add(struct mcast_output *out, struct xbundle *mcast_xbundle) > +{ > + if (out->n >= out->allocated) { > + out->xbundles = x2nrealloc(out->xbundles, &out->allocated, > + sizeof *out->xbundles); > + } > + out->xbundles[out->n++] = mcast_xbundle; > +} > + > +/* Outputs the packet in 'ctx' to all of the output ports in 'out', given > input > + * bundle 'in_xbundle' and the current 'xvlan'. */ > +static void > +mcast_output_finish(struct xlate_ctx *ctx, struct mcast_output *out, > + struct xbundle *in_xbundle, struct xvlan *xvlan) > +{ > + if (out->flood) { > + xlate_normal_flood(ctx, in_xbundle, xvlan); > + } else { > + for (size_t i = 0; i < out->n; i++) { > + output_normal(ctx, out->xbundles[i], xvlan); > + } > + } > + > + free(out->xbundles); > +} > > /* send the packet to ports having the multicast group learned */ > static void > @@ -2697,7 +2746,7 @@ xlate_normal_mcast_send_group(struct xlate_ctx *ctx, > struct mcast_snooping *ms OVS_UNUSED, > struct mcast_group *grp, > struct xbundle *in_xbundle, > - const struct xvlan *xvlan) > + struct mcast_output *out) > OVS_REQ_RDLOCK(ms->rwlock) > { > struct mcast_group_bundle *b; > @@ -2707,7 +2756,7 @@ xlate_normal_mcast_send_group(struct xlate_ctx *ctx, > mcast_xbundle = xbundle_lookup(ctx->xcfg, b->port); > if (mcast_xbundle && mcast_xbundle != in_xbundle) { > xlate_report(ctx, OFT_DETAIL, "forwarding to mcast group > port"); > - output_normal(ctx, mcast_xbundle, xvlan); > + mcast_output_add(out, mcast_xbundle); > } else if (!mcast_xbundle) { > xlate_report(ctx, OFT_WARN, > "mcast group port is unknown, dropping"); > @@ -2723,7 +2772,8 @@ static void > xlate_normal_mcast_send_mrouters(struct xlate_ctx *ctx, > struct mcast_snooping *ms, > struct xbundle *in_xbundle, > - const struct xvlan *xvlan) > + const struct xvlan *xvlan, > + struct mcast_output *out) > OVS_REQ_RDLOCK(ms->rwlock) > { > struct mcast_mrouter_bundle *mrouter; > @@ -2734,7 +2784,7 @@ xlate_normal_mcast_send_mrouters(struct xlate_ctx > *ctx, > if (mcast_xbundle && mcast_xbundle != in_xbundle > && mrouter->vlan == xvlan->v[0].vid) { > xlate_report(ctx, OFT_DETAIL, "forwarding to mcast router > port"); > - output_normal(ctx, mcast_xbundle, xvlan); > + mcast_output_add(out, mcast_xbundle); > } else if (!mcast_xbundle) { > xlate_report(ctx, OFT_WARN, > "mcast router port is unknown, dropping"); > @@ -2753,7 +2803,7 @@ static void > xlate_normal_mcast_send_fports(struct xlate_ctx *ctx, > struct mcast_snooping *ms, > struct xbundle *in_xbundle, > - const struct xvlan *xvlan) > + struct mcast_output *out) > OVS_REQ_RDLOCK(ms->rwlock) > { > struct mcast_port_bundle *fport; > @@ -2763,7 +2813,7 @@ xlate_normal_mcast_send_fports(struct xlate_ctx *ctx, > mcast_xbundle = xbundle_lookup(ctx->xcfg, fport->port); > if (mcast_xbundle && mcast_xbundle != in_xbundle) { > xlate_report(ctx, OFT_DETAIL, "forwarding to mcast flood > port"); > - output_normal(ctx, mcast_xbundle, xvlan); > + mcast_output_add(out, mcast_xbundle); > } else if (!mcast_xbundle) { > xlate_report(ctx, OFT_WARN, > "mcast flood port is unknown, dropping"); > @@ -2779,7 +2829,7 @@ static void > xlate_normal_mcast_send_rports(struct xlate_ctx *ctx, > struct mcast_snooping *ms, > struct xbundle *in_xbundle, > - const struct xvlan *xvlan) > + struct mcast_output *out) > OVS_REQ_RDLOCK(ms->rwlock) > { > struct mcast_port_bundle *rport; > @@ -2792,7 +2842,7 @@ xlate_normal_mcast_send_rports(struct xlate_ctx *ctx, > && mcast_xbundle->ofbundle != in_xbundle->ofbundle) { > xlate_report(ctx, OFT_DETAIL, > "forwarding report to mcast flagged port"); > - output_normal(ctx, mcast_xbundle, xvlan); > + mcast_output_add(out, mcast_xbundle); > } else if (!mcast_xbundle) { > xlate_report(ctx, OFT_WARN, > "mcast port is unknown, dropping the report"); > @@ -2944,8 +2994,11 @@ xlate_normal(struct xlate_ctx *ctx) > } > > if (mcast_snooping_is_membership(flow->tp_src)) { > + struct mcast_output out = MCAST_OUTPUT_INIT; > + > ovs_rwlock_rdlock(&ms->rwlock); > - xlate_normal_mcast_send_mrouters(ctx, ms, in_xbundle, > &xvlan); > + xlate_normal_mcast_send_mrouters(ctx, ms, in_xbundle, > &xvlan, > + &out); > /* RFC4541: section 2.1.1, item 1: A snooping switch > should > * forward IGMP Membership Reports only to those ports > where > * multicast routers are attached. Alternatively stated: > a > @@ -2954,8 +3007,10 @@ xlate_normal(struct xlate_ctx *ctx) > * An administrative control may be provided to override > this > * restriction, allowing the report messages to be > flooded to > * other ports. */ > - xlate_normal_mcast_send_rports(ctx, ms, in_xbundle, > &xvlan); > + xlate_normal_mcast_send_rports(ctx, ms, in_xbundle, &out); > ovs_rwlock_unlock(&ms->rwlock); > + > + mcast_output_finish(ctx, &out, in_xbundle, &xvlan); > } else { > xlate_report(ctx, OFT_DETAIL, "multicast traffic, > flooding"); > xlate_normal_flood(ctx, in_xbundle, &xvlan); > @@ -2968,10 +3023,15 @@ xlate_normal(struct xlate_ctx *ctx) > in_xbundle, ctx->xin->packet); > } > if (is_mld_report(flow, wc)) { > + struct mcast_output out = MCAST_OUTPUT_INIT; > + > ovs_rwlock_rdlock(&ms->rwlock); > - xlate_normal_mcast_send_mrouters(ctx, ms, in_xbundle, > &xvlan); > - xlate_normal_mcast_send_rports(ctx, ms, in_xbundle, > &xvlan); > + xlate_normal_mcast_send_mrouters(ctx, ms, in_xbundle, > &xvlan, > + &out); > + xlate_normal_mcast_send_rports(ctx, ms, in_xbundle, &out); > ovs_rwlock_unlock(&ms->rwlock); > + > + mcast_output_finish(ctx, &out, in_xbundle, &xvlan); > } else { > xlate_report(ctx, OFT_DETAIL, "MLD query, flooding"); > xlate_normal_flood(ctx, in_xbundle, &xvlan); > @@ -2989,6 +3049,8 @@ xlate_normal(struct xlate_ctx *ctx) > } > > /* forwarding to group base ports */ > + struct mcast_output out = MCAST_OUTPUT_INIT; > + > ovs_rwlock_rdlock(&ms->rwlock); > if (flow->dl_type == htons(ETH_TYPE_IP)) { > grp = mcast_snooping_lookup4(ms, flow->nw_dst, vlan); > @@ -2996,20 +3058,24 @@ xlate_normal(struct xlate_ctx *ctx) > grp = mcast_snooping_lookup(ms, &flow->ipv6_dst, vlan); > } > if (grp) { > - xlate_normal_mcast_send_group(ctx, ms, grp, in_xbundle, > &xvlan); > - xlate_normal_mcast_send_fports(ctx, ms, in_xbundle, &xvlan); > - xlate_normal_mcast_send_mrouters(ctx, ms, in_xbundle, &xvlan); > + xlate_normal_mcast_send_group(ctx, ms, grp, in_xbundle, &out); > + xlate_normal_mcast_send_fports(ctx, ms, in_xbundle, &out); > + xlate_normal_mcast_send_mrouters(ctx, ms, in_xbundle, &xvlan, > + &out); > } else { > if (mcast_snooping_flood_unreg(ms)) { > xlate_report(ctx, OFT_DETAIL, > "unregistered multicast, flooding"); > - xlate_normal_flood(ctx, in_xbundle, &xvlan); > + out.flood = true; > } else { > - xlate_normal_mcast_send_mrouters(ctx, ms, in_xbundle, > &xvlan); > - xlate_normal_mcast_send_fports(ctx, ms, in_xbundle, > &xvlan); > + xlate_normal_mcast_send_mrouters(ctx, ms, in_xbundle, > &xvlan, > + &out); > + xlate_normal_mcast_send_fports(ctx, ms, in_xbundle, &out); > } > } > ovs_rwlock_unlock(&ms->rwlock); > + > + mcast_output_finish(ctx, &out, in_xbundle, &xvlan); > } else { > ovs_rwlock_rdlock(&ctx->xbridge->ml->rwlock); > mac = mac_learning_lookup(ctx->xbridge->ml, flow->dl_dst, vlan); > -- > 2.16.1 > > _______________________________________________ > dev mailing list > [email protected] > https://mail.openvswitch.org/mailman/listinfo/ovs-dev > _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
