datpath: Avoid reporting half updated statistics.

[sliver-openvswitch.git] / datapath / datapath.c

diff --git a/datapath/datapath.c b/datapath/datapath.c
index e468198..32572c6 100644 (file)
--- a/datapath/datapath.c
+++ b/datapath/datapath.c
@@ -599,7 +599,11 @@ out:
        /* Update datapath statistics. */
        local_bh_disable();
        stats = per_cpu_ptr(dp->stats_percpu, smp_processor_id());
+
+       write_seqcount_begin(&stats->seqlock);
        (*(u64 *)((u8 *)stats + stats_counter_off))++;
+       write_seqcount_end(&stats->seqlock);
+
        local_bh_enable();
 }
 
@@ -860,7 +864,11 @@ err_kfree_skb:
 err:
        local_bh_disable();
        stats = per_cpu_ptr(dp->stats_percpu, smp_processor_id());
+
+       write_seqcount_begin(&stats->seqlock);
        stats->n_lost++;
+       write_seqcount_end(&stats->seqlock);
+
        local_bh_enable();
 
        return err;
@@ -1394,12 +1402,21 @@ static int get_dp_stats(struct datapath *dp, struct odp_stats __user *statsp)
        stats.max_groups = DP_MAX_GROUPS;
        stats.n_frags = stats.n_hit = stats.n_missed = stats.n_lost = 0;
        for_each_possible_cpu(i) {
-               const struct dp_stats_percpu *s;
-               s = per_cpu_ptr(dp->stats_percpu, i);
-               stats.n_frags += s->n_frags;
-               stats.n_hit += s->n_hit;
-               stats.n_missed += s->n_missed;
-               stats.n_lost += s->n_lost;
+               const struct dp_stats_percpu *percpu_stats;
+               struct dp_stats_percpu local_stats;
+               unsigned seqcount;
+
+               percpu_stats = per_cpu_ptr(dp->stats_percpu, i);
+
+               do {
+                       seqcount = read_seqcount_begin(&percpu_stats->seqlock);
+                       local_stats = *percpu_stats;
+               } while (read_seqcount_retry(&percpu_stats->seqlock, seqcount));
+
+               stats.n_frags += local_stats.n_frags;
+               stats.n_hit += local_stats.n_hit;
+               stats.n_missed += local_stats.n_missed;
+               stats.n_lost += local_stats.n_lost;
        }
        stats.max_miss_queue = DP_MAX_QUEUE_LEN;
        stats.max_action_queue = DP_MAX_QUEUE_LEN;