Re: [PATCH ovpn net v2] ovpn: use monotonic clock for peer keepalive timers

Hi,

On 10/06/2026 20:24, Marco Baffo wrote:
> Replace ktime_get_real_seconds() with ktime_get_seconds() so that
> peer keepalive timeouts are calculated against a monotonic clock
> instead of wall-clock time.
> 
> Because the driver currently uses CLOCK_REALTIME, an administrative
> settimeofday() or an NTP step adjustment that moves the clock forward
> can cause now to exceed last_recv + timeout instantly. This artificially
> expires healthy peers and, depending on userspace configuration, can
> trigger a premature tunnel restart (--keepalive / --ping-restart) or
> client disconnection (--ping-exit). At the same time a backward step
> can delay the detection of dead peers.
> 
> Switching to ktime_get_seconds() avoid both issues.
> 
> Fixes: 411f445fe91d ("ovpn: implement keepalive mechanism")
> Signed-off-by: Marco Baffo <[email protected]>


As discussed offline, we are dropping this patch as we *need* the timer 
to continue also when the host suspends.

Regards,

> ---
> Changes in v2:
> Use ktime_get_seconds() instead of ktime_get_boottime_seconds()
> 
>   drivers/net/ovpn/io.c   | 4 ++--
>   drivers/net/ovpn/peer.c | 4 ++--
>   2 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/ovpn/io.c b/drivers/net/ovpn/io.c
> index a6b777a9c2d9..d0b8f7b95995 100644
> --- a/drivers/net/ovpn/io.c
> +++ b/drivers/net/ovpn/io.c
> @@ -142,7 +142,7 @@ void ovpn_decrypt_post(void *data, int ret)
>   	}
>   
>   	/* keep track of last received authenticated packet for keepalive */
> -	WRITE_ONCE(peer->last_recv, ktime_get_real_seconds());
> +	WRITE_ONCE(peer->last_recv, ktime_get_seconds());
>   
>   	rcu_read_lock();
>   	sock = rcu_dereference(peer->sock);
> @@ -294,7 +294,7 @@ void ovpn_encrypt_post(void *data, int ret)
>   
>   	ovpn_peer_stats_increment_tx(&peer->link_stats, orig_len);
>   	/* keep track of last sent packet for keepalive */
> -	WRITE_ONCE(peer->last_sent, ktime_get_real_seconds());
> +	WRITE_ONCE(peer->last_sent, ktime_get_seconds());
>   	/* skb passed down the stack - don't free it */
>   	skb = NULL;
>   err_unlock:
> diff --git a/drivers/net/ovpn/peer.c b/drivers/net/ovpn/peer.c
> index a09d61296425..caee56cd399a 100644
> --- a/drivers/net/ovpn/peer.c
> +++ b/drivers/net/ovpn/peer.c
> @@ -44,7 +44,7 @@ static void unlock_ovpn(struct ovpn_priv *ovpn,
>    */
>   void ovpn_peer_keepalive_set(struct ovpn_peer *peer, u32 interval, u32 timeout)
>   {
> -	time64_t now = ktime_get_real_seconds();
> +	time64_t now = ktime_get_seconds();
>   
>   	netdev_dbg(peer->ovpn->dev,
>   		   "scheduling keepalive for peer %u: interval=%u timeout=%u\n",
> @@ -1357,7 +1357,7 @@ void ovpn_peer_keepalive_work(struct work_struct *work)
>   {
>   	struct ovpn_priv *ovpn = container_of(work, struct ovpn_priv,
>   					      keepalive_work.work);
> -	time64_t next_run = 0, now = ktime_get_real_seconds();
> +	time64_t next_run = 0, now = ktime_get_seconds();
>   	LLIST_HEAD(release_list);
>   
>   	spin_lock_bh(&ovpn->lock);

-- 
Antonio Quartulli