ofproto-dpif: Ignore non-packet field masks during flow revalidation

Commit bcd2633(ofproto-dpif: Store relevant fields for wildcarding in facet) implements flow revalidation by comparing the newly looked up flow mask with that of the existing facet. The non-packet fields, such as register masks, are always cleared by xlate_actions in the masks stored within facets, but they are not cleared in the newly looked up flow masks, causing otherwise valid flows to be declared as invalid flows and be removed from the datapath. This patch provides a fix. I was able to verify the fix on a system set up by Ying Chen where the bug can be reproduced. Bug #21680 Reported by: Ying Chen <[email protected]> Acked-by: Justin Pettit <[email protected]> Signed-off-by: Andy Zhou <[email protected]>
amuessig · Dec 11, 2013 · eaae2be · eaae2be
1 parent 97e9555
commit eaae2be
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Showing 4 changed files with 16 additions and 2 deletions.
diff --git a/lib/flow.c b/lib/flow.c
@@ -612,6 +612,15 @@ flow_wildcards_init_exact(struct flow_wildcards *wc)
     memset(wc->masks.zeros, 0, sizeof wc->masks.zeros);
 }
 
+/* Clear the metadata and register wildcard masks. They are not packet
+ * header fields. */
+void
+flow_wildcards_clear_non_packet_fields(struct flow_wildcards *wc)
+{
+    memset(&wc->masks.metadata, 0, sizeof wc->masks.metadata);
+    memset(&wc->masks.regs, 0, sizeof wc->masks.regs);
+}
+
 /* Returns true if 'wc' matches every packet, false if 'wc' fixes any bits or
  * fields. */
 bool

diff --git a/lib/flow.h b/lib/flow.h
@@ -241,6 +241,8 @@ struct flow_wildcards {
 void flow_wildcards_init_catchall(struct flow_wildcards *);
 void flow_wildcards_init_exact(struct flow_wildcards *);
 
+void flow_wildcards_clear_non_packet_fields(struct flow_wildcards *);
+
 bool flow_wildcards_is_catchall(const struct flow_wildcards *);
 
 void flow_wildcards_set_reg_mask(struct flow_wildcards *,

diff --git a/ofproto/ofproto-dpif-xlate.c b/ofproto/ofproto-dpif-xlate.c
@@ -2692,8 +2692,7 @@ xlate_actions(struct xlate_in *xin, struct xlate_out *xout)
 
     /* Clear the metadata and register wildcard masks, because we won't
      * use non-header fields as part of the cache. */
-    memset(&wc->masks.metadata, 0, sizeof wc->masks.metadata);
-    memset(&wc->masks.regs, 0, sizeof wc->masks.regs);
+    flow_wildcards_clear_non_packet_fields(wc);
 
 out:
     ovs_rwlock_unlock(&xlate_rwlock);

diff --git a/ofproto/ofproto-dpif.c b/ofproto/ofproto-dpif.c
@@ -4287,6 +4287,10 @@ facet_revalidate(struct facet *facet)
     xlate_in_init(&xin, ofproto, &facet->flow, new_rule, 0, NULL);
     xlate_actions(&xin, &xout);
     flow_wildcards_or(&xout.wc, &xout.wc, &wc);
+    /* Make sure non -packet fields are not masked. If not cleared,
+     * the memcmp() below may fail, causing an otherwise valid facet
+     * to be removed. */
+    flow_wildcards_clear_non_packet_fields(&xout.wc);
 
     /* A facet's slow path reason should only change under dramatic
      * circumstances.  Rather than try to update everything, it's simpler to