[PATCH 6.6 178/254] net: openvswitch: fix data race in ovs_vport_get_upcall_stats

Greg Kroah-Hartman
2026-01-28T15:38:06Z

From: David Yang <mmyangfl@gmail.com>

[ Upstream commit cc4816bdb08639e5cd9acb295a02d6f0f09736b4 ]

In ovs_vport_get_upcall_stats(), some statistics protected by
u64_stats_sync, are read and accumulated in ignorance of possible
u64_stats_fetch_retry() events. These statistics are already accumulated
by u64_stats_inc(). Fix this by reading them into temporary variables
first.

Fixes: 1933ea365aa7 ("net: openvswitch: Add support to count upcall packets")
Signed-off-by: David Yang <mmyangfl@gmail.com>
Acked-by: Ilya Maximets <i.maximets@ovn.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Aaron Conole <aconole@redhat.com>
Link: https://patch.msgid.link/20260121072932.2360971-1-mmyangfl@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/openvswitch/vport.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/net/openvswitch/vport.c b/net/openvswitch/vport.c
index 972ae01a70f76..0faa6e097829c 100644
--- a/net/openvswitch/vport.c
+++ b/net/openvswitch/vport.c
@@ -310,22 +310,23 @@ void ovs_vport_get_stats(struct vport *vport, struct ovs_vport_stats *stats)
*/
int ovs_vport_get_upcall_stats(struct vport *vport, struct sk_buff *skb)
{
+ u64 tx_success = 0, tx_fail = 0;
struct nlattr *nla;
int i;

- __u64 tx_success = 0;
- __u64 tx_fail = 0;
-
for_each_possible_cpu(i) {
const struct vport_upcall_stats_percpu *stats;
+ u64 n_success, n_fail;
unsigned int start;

stats = per_cpu_ptr(vport->upcall_stats, i);
do {
start = u64_stats_fetch_begin(&stats->syncp);
- tx_success += u64_stats_read(&stats->n_success);
- tx_fail += u64_stats_read(&stats->n_fail);
+ n_success = u64_stats_read(&stats->n_success);
+ n_fail = u64_stats_read(&stats->n_fail);
} while (u64_stats_fetch_retry(&stats->syncp, start));
+ tx_success += n_success;
+ tx_fail += n_fail;
}

nla = nla_nest_start_noflag(skb, OVS_VPORT_ATTR_UPCALL_STATS);
--
2.51.0