While the values are written only by a single thread, reading them
concurrently might produce incorrect results, given the lack of 64-bit
atomic loads on 32-bit systems.
This fix prevent unconsistent reads of 64-bit values on 32-bit systems.
Signed-off-by: Daniele Di Proietto <diproiet...@vmware.com>
---
lib/dpif-netdev.c | 48 +++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 41 insertions(+), 7 deletions(-)
diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
index 2637e8d..ba677eb 100644
--- a/lib/dpif-netdev.c
+++ b/lib/dpif-netdev.c
@@ -64,6 +64,7 @@
#include "sset.h"
#include "timeval.h"
#include "tnl-arp-cache.h"
+#include "u64-stats-sync.h"
#include "unixctl.h"
#include "util.h"
#include "openvswitch/vlog.h"
@@ -301,6 +302,9 @@ struct dp_netdev_flow {
/* Statistics. */
struct dp_netdev_flow_stats stats;
+ /* Used to protect 'stats'. Only guarantees consistency of single stats
+ * members, not of the structure as a whole */
+ struct u64_stats_sync stats_lock;
/* Actions. */
OVSRCU_TYPE(struct dp_netdev_actions *) actions;
@@ -382,6 +386,9 @@ struct dp_netdev_pmd_thread {
/* Statistics. */
struct dp_netdev_pmd_stats stats;
+ /* Used to protect 'stats'. Only guarantees consistency of single stats
+ * members, not of the structure as a whole */
+ struct u64_stats_sync stats_lock;
struct latch exit_latch; /* For terminating the pmd thread. */
atomic_uint change_seq; /* For reloading pmd ports. */
@@ -754,10 +761,19 @@ dpif_netdev_get_stats(const struct dpif *dpif, struct
dpif_dp_stats *stats)
stats->n_flows = stats->n_hit = stats->n_missed = stats->n_lost = 0;
CMAP_FOR_EACH (pmd, node, &dp->poll_threads) {
+ struct dp_netdev_pmd_stats s;
+ uint32_t c;
+
+ do {
+ c = u64_stats_read_begin(&pmd->stats_lock);
+ s = pmd->stats;
+ } while (!u64_stats_read_correct(&pmd->stats_lock, c));
+
stats->n_flows += cmap_count(&pmd->flow_table);
- stats->n_hit += pmd->stats.n[DP_STAT_HIT];
- stats->n_missed += pmd->stats.n[DP_STAT_MISS];
- stats->n_lost += pmd->stats.n[DP_STAT_LOST];
+
+ stats->n_hit += s.n[DP_STAT_HIT];
+ stats->n_missed += s.n[DP_STAT_MISS];
+ stats->n_lost += s.n[DP_STAT_LOST];
}
stats->n_masks = UINT32_MAX;
stats->n_mask_hit = UINT64_MAX;
@@ -1548,10 +1564,15 @@ static void
get_dpif_flow_stats(const struct dp_netdev_flow *netdev_flow,
struct dpif_flow_stats *stats)
{
- stats->n_packets = netdev_flow->stats.packet_count;
- stats->n_bytes = netdev_flow->stats.byte_count;
- stats->used = netdev_flow->stats.used;
- stats->tcp_flags = netdev_flow->stats.tcp_flags;
+ uint32_t c;
+ do {
+ c = u64_stats_read_begin(&netdev_flow->stats_lock);
+
+ stats->n_packets = netdev_flow->stats.packet_count;
+ stats->n_bytes = netdev_flow->stats.byte_count;
+ stats->used = netdev_flow->stats.used;
+ stats->tcp_flags = netdev_flow->stats.tcp_flags;
+ } while (!u64_stats_read_correct(&netdev_flow->stats_lock, c));
}
/* Converts to the dpif_flow format, using 'key_buf' and 'mask_buf' for
@@ -1735,6 +1756,7 @@ dp_netdev_flow_add(struct dp_netdev_pmd_thread *pmd,
/* Do not allocate extra space. */
flow = xmalloc(sizeof *flow - sizeof flow->cr.flow.mf + mask.len);
memset(&flow->stats, 0, sizeof flow->stats);
+ memset(&flow->stats_lock, 0, sizeof flow->stats_lock);
flow->dead = false;
*CONST_CAST(int *, &flow->pmd_id) = pmd->core_id;
*CONST_CAST(struct flow *, &flow->flow) = match->flow;
@@ -2670,18 +2692,30 @@ dp_netdev_flow_used(struct dp_netdev_flow *netdev_flow,
int cnt, int size,
uint16_t tcp_flags)
{
long long int now = time_msec();
+ uint32_t c;
+
+ c = u64_stats_write_begin(&netdev_flow->stats_lock);
netdev_flow->stats.used = MAX(now, netdev_flow->stats.used);
netdev_flow->stats.packet_count += cnt;
netdev_flow->stats.byte_count += size;
netdev_flow->stats.tcp_flags |= tcp_flags;
+
+ u64_stats_write_end(&netdev_flow->stats_lock, c);
}
static void
dp_netdev_count_packet(struct dp_netdev_pmd_thread *pmd,
enum dp_stat_type type, int cnt)
{
+ uint32_t c;
+
+ if (!cnt)
+ return;
+
+ c = u64_stats_write_begin(&pmd->stats_lock);
pmd->stats.n[type] += cnt;
+ u64_stats_write_end(&pmd->stats_lock, c);
}
static int
--
2.1.4
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