* Re: [PATCH net v2] net: openvswitch: fix data race in ovs_vport_get_upcall_stats
2026-01-21 7:29 [PATCH net v2] net: openvswitch: fix data race in ovs_vport_get_upcall_stats David Yang
@ 2026-01-21 13:27 ` Ilya Maximets
2026-01-21 13:29 ` Eric Dumazet
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: Ilya Maximets @ 2026-01-21 13:27 UTC (permalink / raw)
To: David Yang, netdev
Cc: i.maximets, Aaron Conole, Eelco Chaudron, David S. Miller,
Eric Dumazet, Jakub Kicinski, Paolo Abeni, Simon Horman,
wangchuanlei, dev, linux-kernel
On 1/21/26 8:29 AM, David Yang wrote:
> 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>
> ---
> v1: https://lore.kernel.org/r/20260119181339.1847451-1-mmyangfl@gmail.com
> - use u64 instead of __u64
> 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 6bbbc16ab778..f0ce8ce1dce0 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));
Would be good to have an empty line here for readability, but a new version
just for this seems a bit excessive.
Either way:
Acked-by: Ilya Maximets <i.maximets@ovn.org>
> + tx_success += n_success;
> + tx_fail += n_fail;
> }
>
> nla = nla_nest_start_noflag(skb, OVS_VPORT_ATTR_UPCALL_STATS);
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH net v2] net: openvswitch: fix data race in ovs_vport_get_upcall_stats
2026-01-21 7:29 [PATCH net v2] net: openvswitch: fix data race in ovs_vport_get_upcall_stats David Yang
2026-01-21 13:27 ` Ilya Maximets
@ 2026-01-21 13:29 ` Eric Dumazet
2026-01-21 13:54 ` Aaron Conole
2026-01-22 12:00 ` patchwork-bot+netdevbpf
3 siblings, 0 replies; 5+ messages in thread
From: Eric Dumazet @ 2026-01-21 13:29 UTC (permalink / raw)
To: David Yang
Cc: netdev, Aaron Conole, Eelco Chaudron, Ilya Maximets,
David S. Miller, Jakub Kicinski, Paolo Abeni, Simon Horman,
wangchuanlei, dev, linux-kernel
On Wed, Jan 21, 2026 at 8:32 AM David Yang <mmyangfl@gmail.com> wrote:
>
> 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>
Reviewed-by: Eric Dumazet <edumazet@google.com>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH net v2] net: openvswitch: fix data race in ovs_vport_get_upcall_stats
2026-01-21 7:29 [PATCH net v2] net: openvswitch: fix data race in ovs_vport_get_upcall_stats David Yang
2026-01-21 13:27 ` Ilya Maximets
2026-01-21 13:29 ` Eric Dumazet
@ 2026-01-21 13:54 ` Aaron Conole
2026-01-22 12:00 ` patchwork-bot+netdevbpf
3 siblings, 0 replies; 5+ messages in thread
From: Aaron Conole @ 2026-01-21 13:54 UTC (permalink / raw)
To: David Yang
Cc: netdev, Eelco Chaudron, Ilya Maximets, David S. Miller,
Eric Dumazet, Jakub Kicinski, Paolo Abeni, Simon Horman,
wangchuanlei, dev, linux-kernel
David Yang <mmyangfl@gmail.com> writes:
> 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>
> ---
> v1: https://lore.kernel.org/r/20260119181339.1847451-1-mmyangfl@gmail.com
> - use u64 instead of __u64
> net/openvswitch/vport.c | 11 ++++++-----
> 1 file changed, 6 insertions(+), 5 deletions(-)
Thanks for the patch - I did a spot-check of the rest of the module with
the following:
~/git/linux/net/openvswitch$ grep -nr 'while\(.*fetch.*\)'
and didn't find any other places that seemed to duplicate this
mistaken read pattern (at least in the OVS kernel module).
Reviewed-by: Aaron Conole <aconole@redhat.com>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH net v2] net: openvswitch: fix data race in ovs_vport_get_upcall_stats
2026-01-21 7:29 [PATCH net v2] net: openvswitch: fix data race in ovs_vport_get_upcall_stats David Yang
` (2 preceding siblings ...)
2026-01-21 13:54 ` Aaron Conole
@ 2026-01-22 12:00 ` patchwork-bot+netdevbpf
3 siblings, 0 replies; 5+ messages in thread
From: patchwork-bot+netdevbpf @ 2026-01-22 12:00 UTC (permalink / raw)
To: Yangfl
Cc: netdev, aconole, echaudro, i.maximets, davem, edumazet, kuba,
pabeni, horms, wangchuanlei, dev, linux-kernel
Hello:
This patch was applied to netdev/net.git (main)
by Paolo Abeni <pabeni@redhat.com>:
On Wed, 21 Jan 2026 15:29:26 +0800 you wrote:
> 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>
>
> [...]
Here is the summary with links:
- [net,v2] net: openvswitch: fix data race in ovs_vport_get_upcall_stats
https://git.kernel.org/netdev/net/c/cc4816bdb086
You are awesome, thank you!
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^ permalink raw reply [flat|nested] 5+ messages in thread