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Date: Mon, 7 Oct 2013 15:34:47 +0900
From: Simon Horman <horms@...ge.net.au>
To: Ben Pfaff <blp@...ira.com>
Cc: dev@...nvswitch.org, netdev@...r.kernel.org,
Jesse Gross <jesse@...ira.com>,
Pravin B Shelar <pshelar@...ira.com>,
Ravi K <rkerur@...il.com>,
Isaku Yamahata <yamahata@...inux.co.jp>,
Joe Stringer <joe@...d.net.nz>
Subject: Re: [PATCH v2.42 1/5] odp: Allow VLAN actions after MPLS actions
On Fri, Oct 04, 2013 at 09:21:33AM -0700, Ben Pfaff wrote:
> On Fri, Oct 04, 2013 at 05:09:56PM +0900, Simon Horman wrote:
> > From: Joe Stringer <joe@...d.net.nz>
> >
> > OpenFlow 1.1 and 1.2, and 1.3 differ in their handling of MPLS actions in the
> > presence of VLAN tags. To allow correct behaviour to be committed in
> > each situation, this patch adds a second round of VLAN tag action
> > handling to commit_odp_actions(), which occurs after MPLS actions. This
> > is implemented with a new field in 'struct xlate_in' called 'vlan_tci'.
> >
> > When an push_mpls action is composed, the flow's current VLAN state is
> > stored into xin->vlan_tci, and flow->vlan_tci is set to 0 (pop_vlan). If
> > a VLAN tag is present, it is stripped; if not, then there is no change.
> > Any later modifications to the VLAN state is written to xin->vlan_tci.
> > When committing the actions, flow->vlan_tci is used before MPLS actions,
> > and xin->vlan_tci is used afterwards. This retains the current datapath
> > behaviour, but allows VLAN actions to be applied in a more flexible
> > manner.
> >
> > Both before and after this patch MPLS LSEs are pushed onto a packet after
> > any VLAN tags that may be present. This is the behaviour described in
> > OpenFlow 1.1 and 1.2. OpenFlow 1.3 specifies that MPLS LSEs should be
> > pushed onto a packet before any VLAN tags that are present. Support
> > for this will be added by a subsequent patch that makes use of
> > the infrastructure added by this patch.
> >
> > Signed-off-by: Joe Stringer <joe@...d.net.nz>
> > Signed-off-by: Simon Horman <horms@...ge.net.au>
>
> I noticed a couple more minor points.
>
> First, it seems to me that the "vlan_tci" member that this adds to
> xlate_in could go in xlate_ctx just as well. I would prefer that,
> because (as far as I can tell) there is no reason for the client to use
> any value other than flow->vlan_tci here, and putting it in xlate_ctx
> hides it from the client.
Thanks. Yes I agree that is a good idea.
> Thanks for rearranging the code and updating the comment in
> do_xlate_actions(). It makes the operation clearer. But now that it's
> clear I have an additional question. Does it really make sense to have
> 'vlan_tci' as only a local variable in do_xlate_actions()? Presumably,
> MPLS and VLANs should interact the same way regardless of whether they
> are separated by resubmits or goto_tables. That is, I suspect that this
> is xlate_ctx state, not local state.
Agreed.
What I have done is to make an incremental patch which:
1. Moves the 'vlan_tci' member of strict xlate_in to
be the 'final_vlan_tci' member of struct xlate_ctx.
2. Moves the 'vlan_tci' local variable of do_xlate_actions()
to be the 'next_vlan_tci' member of struct xlate_ctx.
3. Restructures the comments surrounding the logic of the vlan_tci
code that this patch adds mostly as comments for the new
members of struct xlate_ctx. I hope things are (still?) clear.
For reference, the incremental patch I have so far is as follows.
I will squash it into this patch before reposting this series.
commit d57735cec0d3e53c7479725ae1cf825563902c30
Author: Simon Horman <horms@...ge.net.au>
Date: Mon Oct 7 14:30:28 2013 +0900
Move vlan state into struct xlate_ctx
1. Add final_vlan_tci member to struct xlate_ctx instead of vlan_tci member
struct xlate_xin. This seems to be a better palace for it as it does
not need to be accessible from the caller.
2. Move local vlan_tci variable of do_xlate_actions() to be the
next_vlan_tci member of strict xlate_ctx. This allows for it to work
across resubmit actions and goto table instructions.
As suggested by Ben Pfaff
diff --git a/ofproto/ofproto-dpif-xlate.c b/ofproto/ofproto-dpif-xlate.c
index 2afd760..845c6fe 100644
--- a/ofproto/ofproto-dpif-xlate.c
+++ b/ofproto/ofproto-dpif-xlate.c
@@ -172,6 +172,37 @@ struct xlate_ctx {
odp_port_t sflow_odp_port; /* Output port for composing sFlow action. */
uint16_t user_cookie_offset;/* Used for user_action_cookie fixup. */
bool exit; /* No further actions should be processed. */
+
+ /* The final vlan_tci state.
+ *
+ * The value of the vlan TCI prior to the committing of ODP MPLS
+ * actions should be stored in 'xin->flow->vlan_tci'.
+ *
+ * The final value of the VLAN TCI should be stored in 'vlan_tci'. And
+ * is if the value of 'vlan_tci' and 'xin->flow->vlan_tci' differ then
+ * VLAN ODP actions will be committed after any MPLS actions regardless
+ * of whether VLAN actions were also committed before the MPLS actions or
+ * not.
+ *
+ * This mechanism allows a VLAN tag to be popped before pushing
+ * an MPLS LSE and then the same VLAN tag pushed after pushing
+ * the MPLS LSE. In this way it is possible to push an MPLS LSE
+ * before an existing VLAN tag. Moreover this mechanism allows
+ * the order in which VLAN tags and MPLS LSEs are pushed. */
+ ovs_be16 final_vlan_tci;
+
+ /* The next vlan_tci state.
+ *
+ * This value this variable points to updated each time an
+ * action updates the VLAN tci.
+ *
+ * This variable initially points to 'xin->flow->vlan_tci' so that ODP
+ * VLAN actions are committed before any MPLS actions. When an MPLS
+ * action is composed 'next_vlan_tci' is updated to point to
+ * 'final_vlan_tci'. This causes subsequent VLAN actions to be
+ * committed after MPLS actions. */
+ ovs_be16 *next_vlan_tci;
+
};
/* A controller may use OFPP_NONE as the ingress port to indicate that
@@ -982,7 +1013,7 @@ static void
output_normal(struct xlate_ctx *ctx, const struct xbundle *out_xbundle,
uint16_t vlan)
{
- ovs_be16 *flow_tci = &ctx->xin->vlan_tci;
+ ovs_be16 *flow_tci = &ctx->final_vlan_tci;
uint16_t vid;
ovs_be16 tci, old_tci;
struct xport *xport;
@@ -1258,7 +1289,7 @@ xlate_normal(struct xlate_ctx *ctx)
/* Drop malformed frames. */
if (flow->dl_type == htons(ETH_TYPE_VLAN) &&
- !(ctx->xin->vlan_tci & htons(VLAN_CFI))) {
+ !(ctx->final_vlan_tci & htons(VLAN_CFI))) {
if (ctx->xin->packet != NULL) {
static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
VLOG_WARN_RL(&rl, "bridge %s: dropping packet with partial "
@@ -1282,7 +1313,7 @@ xlate_normal(struct xlate_ctx *ctx)
}
/* Check VLAN. */
- vid = vlan_tci_to_vid(ctx->xin->vlan_tci);
+ vid = vlan_tci_to_vid(ctx->final_vlan_tci);
if (!input_vid_is_valid(vid, in_xbundle, ctx->xin->packet != NULL)) {
xlate_report(ctx, "disallowed VLAN VID for this input port, dropping");
return;
@@ -1540,7 +1571,7 @@ compose_output_action__(struct xlate_ctx *ctx, ofp_port_t ofp_port,
const struct xport *xport = get_ofp_port(ctx->xbridge, ofp_port);
struct flow_wildcards *wc = &ctx->xout->wc;
struct flow *flow = &ctx->xin->flow;
- ovs_be16 flow_vlan_tci, xin_vlan_tci;
+ ovs_be16 flow_vlan_tci, vlan_tci;
uint32_t flow_pkt_mark;
uint8_t flow_nw_tos;
odp_port_t out_port, odp_port;
@@ -1609,7 +1640,7 @@ compose_output_action__(struct xlate_ctx *ctx, ofp_port_t ofp_port,
}
flow_vlan_tci = flow->vlan_tci;
- xin_vlan_tci = ctx->xin->vlan_tci;
+ vlan_tci = ctx->final_vlan_tci;
flow_pkt_mark = flow->pkt_mark;
flow_nw_tos = flow->nw_tos;
@@ -1649,20 +1680,20 @@ compose_output_action__(struct xlate_ctx *ctx, ofp_port_t ofp_port,
wc->masks.vlan_tci |= htons(VLAN_VID_MASK | VLAN_CFI);
}
vlandev_port = vsp_realdev_to_vlandev(ctx->xbridge->ofproto, ofp_port,
- ctx->xin->vlan_tci);
+ ctx->final_vlan_tci);
if (vlandev_port == ofp_port) {
out_port = odp_port;
} else {
out_port = ofp_port_to_odp_port(ctx->xbridge, vlandev_port);
flow->vlan_tci = htons(0);
- ctx->xin->vlan_tci = htons(0);
+ ctx->final_vlan_tci = htons(0);
}
}
if (out_port != ODPP_NONE) {
commit_odp_actions(flow, &ctx->base_flow,
&ctx->xout->odp_actions, &ctx->xout->wc,
- &ctx->mpls_depth_delta, ctx->xin->vlan_tci);
+ &ctx->mpls_depth_delta, ctx->final_vlan_tci);
nl_msg_put_odp_port(&ctx->xout->odp_actions, OVS_ACTION_ATTR_OUTPUT,
out_port);
@@ -1674,7 +1705,7 @@ compose_output_action__(struct xlate_ctx *ctx, ofp_port_t ofp_port,
out:
/* Restore flow */
flow->vlan_tci = flow_vlan_tci;
- ctx->xin->vlan_tci = xin_vlan_tci;
+ ctx->final_vlan_tci = vlan_tci;
flow->pkt_mark = flow_pkt_mark;
flow->nw_tos = flow_nw_tos;
}
@@ -1819,7 +1850,7 @@ execute_controller_action(struct xlate_ctx *ctx, int len,
commit_odp_actions(&ctx->xin->flow, &ctx->base_flow,
&ctx->xout->odp_actions, &ctx->xout->wc,
- &ctx->mpls_depth_delta, ctx->xin->vlan_tci);
+ &ctx->mpls_depth_delta, ctx->final_vlan_tci);
odp_execute_actions(NULL, packet, &key, ctx->xout->odp_actions.data,
ctx->xout->odp_actions.size, NULL, NULL);
@@ -2207,7 +2238,7 @@ xlate_sample_action(struct xlate_ctx *ctx,
commit_odp_actions(&ctx->xin->flow, &ctx->base_flow,
&ctx->xout->odp_actions, &ctx->xout->wc,
- &ctx->mpls_depth_delta, ctx->xin->vlan_tci);
+ &ctx->mpls_depth_delta, ctx->final_vlan_tci);
compose_flow_sample_cookie(os->probability, os->collector_set_id,
os->obs_domain_id, os->obs_point_id, &cookie);
@@ -2236,13 +2267,14 @@ may_receive(const struct xport *xport, struct xlate_ctx *ctx)
}
static void
-vlan_tci_restore(struct xlate_in *xin, ovs_be16 *tci_ptr, ovs_be16 orig_tci)
+vlan_tci_restore(struct xlate_ctx *ctx, ovs_be16 orig_tci)
{
/* If MPLS actions were executed after vlan actions then
* copy the final vlan_tci out and restore the intermediate VLAN state. */
- if (xin->flow.vlan_tci != orig_tci && tci_ptr == &xin->vlan_tci) {
- xin->vlan_tci = xin->flow.vlan_tci;
- xin->flow.vlan_tci = orig_tci;
+ if (ctx->xin->flow.vlan_tci != orig_tci &&
+ ctx->next_vlan_tci == &ctx->final_vlan_tci) {
+ ctx->final_vlan_tci = ctx->xin->flow.vlan_tci;
+ ctx->xin->flow.vlan_tci = orig_tci;
}
}
@@ -2252,19 +2284,8 @@ do_xlate_actions(const struct ofpact *ofpacts, size_t ofpacts_len,
{
struct flow_wildcards *wc = &ctx->xout->wc;
struct flow *flow = &ctx->xin->flow;
- ovs_be16 *vlan_tci;
const struct ofpact *a;
-
- /* VLAN actions are stored in '*vlan_tci'. This variable initially
- * points to 'xin->flow->vlan_tci', so that VLAN actions are applied
- * before any MPLS actions. When an MPLS action is translated,
- * 'vlan_tci' is updated to point to 'xin->vlan_tci'. This causes later
- * VLAN actions to be applied after MPLS actions. For each iteration
- * of the loop 'xin->vlan_tci' is updated to reflect the final VLAN
- * state of the flow. */
- vlan_tci = &ctx->xin->flow.vlan_tci;
-
OFPACT_FOR_EACH (a, ofpacts, ofpacts_len) {
struct ofpact_controller *controller;
const struct ofpact_metadata *metadata;
@@ -2274,7 +2295,7 @@ do_xlate_actions(const struct ofpact *ofpacts, size_t ofpacts_len,
}
/* Update the final vlan state to match the current state. */
- ctx->xin->vlan_tci = *vlan_tci;
+ ctx->final_vlan_tci = *ctx->next_vlan_tci;
switch (a->type) {
case OFPACT_OUTPUT:
@@ -2299,28 +2320,28 @@ do_xlate_actions(const struct ofpact *ofpacts, size_t ofpacts_len,
case OFPACT_SET_VLAN_VID:
wc->masks.vlan_tci |= htons(VLAN_VID_MASK | VLAN_CFI);
- *vlan_tci &= ~htons(VLAN_VID_MASK);
- *vlan_tci |= (htons(ofpact_get_SET_VLAN_VID(a)->vlan_vid)
+ *ctx->next_vlan_tci &= ~htons(VLAN_VID_MASK);
+ *ctx->next_vlan_tci |= (htons(ofpact_get_SET_VLAN_VID(a)->vlan_vid)
| htons(VLAN_CFI));
break;
case OFPACT_SET_VLAN_PCP:
wc->masks.vlan_tci |= htons(VLAN_VID_MASK | VLAN_CFI);
- *vlan_tci &= ~htons(VLAN_PCP_MASK);
- *vlan_tci |=
+ *ctx->next_vlan_tci &= ~htons(VLAN_PCP_MASK);
+ *ctx->next_vlan_tci |=
htons((ofpact_get_SET_VLAN_PCP(a)->vlan_pcp << VLAN_PCP_SHIFT)
| VLAN_CFI);
break;
case OFPACT_STRIP_VLAN:
memset(&wc->masks.vlan_tci, 0xff, sizeof wc->masks.vlan_tci);
- *vlan_tci = htons(0);
+ *ctx->next_vlan_tci = htons(0);
break;
case OFPACT_PUSH_VLAN:
/* XXX 802.1AD(QinQ) */
memset(&wc->masks.vlan_tci, 0xff, sizeof wc->masks.vlan_tci);
- *vlan_tci = htons(VLAN_CFI);
+ *ctx->next_vlan_tci = htons(VLAN_CFI);
break;
case OFPACT_SET_ETH_SRC:
@@ -2391,20 +2412,20 @@ do_xlate_actions(const struct ofpact *ofpacts, size_t ofpacts_len,
case OFPACT_REG_MOVE: {
ovs_be16 orig_tci = flow->vlan_tci;
nxm_execute_reg_move(ofpact_get_REG_MOVE(a), flow, wc);
- vlan_tci_restore(ctx->xin, vlan_tci, orig_tci);
+ vlan_tci_restore(ctx, orig_tci);
break;
}
case OFPACT_REG_LOAD: {
ovs_be16 orig_tci = flow->vlan_tci;
nxm_execute_reg_load(ofpact_get_REG_LOAD(a), flow);
- vlan_tci_restore(ctx->xin, vlan_tci, orig_tci);
+ vlan_tci_restore(ctx, orig_tci);
break;
}
case OFPACT_STACK_PUSH: {
ovs_be16 orig_tci = flow->vlan_tci;
- flow->vlan_tci = *vlan_tci;
+ flow->vlan_tci = *ctx->next_vlan_tci;
nxm_execute_stack_push(ofpact_get_STACK_PUSH(a), flow, wc,
&ctx->stack);
flow->vlan_tci = orig_tci;
@@ -2415,7 +2436,7 @@ do_xlate_actions(const struct ofpact *ofpacts, size_t ofpacts_len,
ovs_be16 orig_tci = flow->vlan_tci;
nxm_execute_stack_pop(ofpact_get_STACK_POP(a), flow, wc,
&ctx->stack);
- vlan_tci_restore(ctx->xin, vlan_tci, orig_tci);
+ vlan_tci_restore(ctx, orig_tci);
break;
}
@@ -2433,11 +2454,11 @@ do_xlate_actions(const struct ofpact *ofpacts, size_t ofpacts_len,
* Do not save and therefore pop the VLAN tags if the MPLS LSE
* should be pushed before any VLAN tags that are present.
* This is the behaviour described for OpenFlow 1.3. */
- ctx->xin->vlan_tci = *vlan_tci;
+ ctx->final_vlan_tci = *ctx->next_vlan_tci;
if (!oam->mpls_before_vlan) {
flow->vlan_tci = htons(0);
}
- vlan_tci = &ctx->xin->vlan_tci;
+ ctx->next_vlan_tci = &ctx->final_vlan_tci;
break;
}
@@ -2540,7 +2561,6 @@ xlate_in_init(struct xlate_in *xin, struct ofproto_dpif *ofproto,
{
xin->ofproto = ofproto;
xin->flow = *flow;
- xin->vlan_tci = flow->vlan_tci;
xin->packet = packet;
xin->may_learn = packet != NULL;
xin->rule = rule;
@@ -2770,6 +2790,8 @@ xlate_actions(struct xlate_in *xin, struct xlate_out *xout)
ctx.table_id = 0;
ctx.exit = false;
ctx.mpls_depth_delta = 0;
+ ctx.final_vlan_tci = ctx->xin->flow.vlan_tci;
+ ctx.next_vlan_tci = &ctx->xin->flow.vlan_tci;
if (xin->ofpacts) {
ofpacts = xin->ofpacts;
diff --git a/ofproto/ofproto-dpif-xlate.h b/ofproto/ofproto-dpif-xlate.h
index 54fd36d..6403f50 100644
--- a/ofproto/ofproto-dpif-xlate.h
+++ b/ofproto/ofproto-dpif-xlate.h
@@ -60,11 +60,6 @@ struct xlate_in {
* this flow when actions change header fields. */
struct flow flow;
- /* If MPLS and VLAN actions were both present in the translation, and VLAN
- * actions should occur after the MPLS actions, then this field is used
- * to store the final vlan_tci state. */
- ovs_be16 vlan_tci;
-
/* The packet corresponding to 'flow', or a null pointer if we are
* revalidating without a packet to refer to. */
const struct ofpbuf *packet;
--
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