dpif-linux: fix the size of n_masks

The command ovs-dpctl can wrongly output the masks even if the
datapath does not implement mega flows. In this case the output
will be similar to the following:

system@ovs-system:
	lookups: hit:14 missed:41 lost:0
	flows: 0
	masks: hit:18446744073709551615 total:4294967295
		hit/pkt:335395346794719104.00
	port 0: ovs-system (internal)
	port 1: gre_system (gre: df_default=false, ttl=0)
	port 2: ots-br0 (internal)
	port 3: int0 (internal)
	port 4: vnet0
	port 5: vnet1

The problem depends on the fact that n_masks stats is stored as a
uint32 in the struct ovs_dp_megaflow_stats and as a uint64 in the
struct dpif_dp_stats. UINT32_MAX instead of UINT64_MAX should be
used to detect if the datapath supports megaflows or not.

Signed-off-by: Francesco Fusco <ffusco@redhat.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>

AUTHORS

@@ -39,6 +39,7 @@ Edouard Bourguignon     madko@linuxed.net
 Edward Tomasz Napierała trasz@freebsd.org
 Ethan Jackson           ethan@nicira.com
 Flavio Leitner          fbl@redhat.com
+Francesco Fusco         ffusco@redhat.com
 FUJITA Tomonori         fujita.tomonori@lab.ntt.co.jp
 Gaetano Catalli         gaetano.catalli@gmail.com
 Geoffrey Wossum         gwossum@acm.org

lib/dpif-netdev.c

@@ -407,7 +407,7 @@ dpif_netdev_get_stats(const struct dpif *dpif, struct dpif_dp_stats *stats)
     stats->n_hit = dp->n_hit;
     stats->n_missed = dp->n_missed;
     stats->n_lost = dp->n_lost;
-    stats->n_masks = UINT64_MAX;
+    stats->n_masks = UINT32_MAX;
     stats->n_mask_hit = UINT64_MAX;
     ovs_mutex_unlock(&dp_netdev_mutex);
 

lib/dpif.h

@@ -413,9 +413,9 @@ struct dpif_dp_stats {
     uint64_t n_missed;          /* Number of flow table misses. */
     uint64_t n_lost;            /* Number of misses not sent to userspace. */
     uint64_t n_flows;           /* Number of flows present. */
-    uint64_t n_masks;           /* Number of mega flow masks. */
     uint64_t n_mask_hit;        /* Number of mega flow masks visited for
                                    flow table matches. */
+    uint32_t n_masks;           /* Number of mega flow masks. */
 };
 int dpif_get_dp_stats(const struct dpif *, struct dpif_dp_stats *);
 

utilities/ovs-dpctl.c

@@ -561,11 +561,11 @@ show_dpif(struct dpif *dpif)
         printf("\tlookups: hit:%"PRIu64" missed:%"PRIu64" lost:%"PRIu64"\n"
                "\tflows: %"PRIu64"\n",
                stats.n_hit, stats.n_missed, stats.n_lost, stats.n_flows);
-        if (stats.n_masks != UINT64_MAX) {
+        if (stats.n_masks != UINT32_MAX) {
             uint64_t n_pkts = stats.n_hit + stats.n_missed;
             double avg = n_pkts ? (double) stats.n_mask_hit / n_pkts : 0.0;
 
-            printf("\tmasks: hit:%"PRIu64" total:%"PRIu64" hit/pkt:%.2f\n",
+            printf("\tmasks: hit:%"PRIu64" total:%"PRIu32" hit/pkt:%.2f\n",
                    stats.n_mask_hit, stats.n_masks, avg);
         }
     }