Re: [PATCH v21 19/24] ovpn: implement peer add/get/dump/delete via netlink

On 04/03/2025 15:35, Sabrina Dubroca wrote:

2025-03-04, 01:33:49 +0100, Antonio Quartulli wrote:

quoted

@@ -1317,11 +1336,16 @@ void ovpn_peer_keepalive_work(struct work_struct *work)
  
  	/* prevent rearming if the interface is being destroyed */
  	if (next_run > 0 && ovpn->registered) {
+		time64_t delta = next_run - now;
+
  		netdev_dbg(ovpn->dev,
  			   "scheduling keepalive work: now=%llu next_run=%llu delta=%llu\n",
-			   next_run, now, next_run - now);
+			   next_run, now, delta > 0 ? delta : 0);
+		/* due to the waiting above, the next_run deadline may have
+		 * passed: in this case we reschedule the worker immediately
+		 */

I don't understand this bit. I don't see what waiting you're refering
to (in particular within this patch), and I don't see how we could get
next_run < now based on how next_run is computed in
ovpn_peer_keepalive_work_single (next_run1/next_run2 is always set to
now + X or something that we just tested to be > now).

Am I missing something?

Sorry - this is just noise.
Before getting to this final solution, I went for an intermediate implementation where I was calling wait_for_completion() on a list of removed peers (this is "the waiting above" the comment refers to).

Since I had no clue how long I waited, I had to update 'now'.
But at that point there was a chance that we had passed the deadline for the next run, hence ending up with a negative delta.

This said, all this logic was thrown away, but I accidentally kept the check on delta (that I even argued about in a previous email when you saw the bogus ternary-op)

so yeah, the ternary-op can go away.

Thanks for double/triple checking with me.

Cheers,

quoted

  		schedule_delayed_work(&ovpn->keepalive_work,
-				      (next_run - now) * HZ);
+				      delta * HZ > 0 ? delta * HZ : 0);
  	}
  	unlock_ovpn(ovpn, &release_list);
  }

-- 
Antonio Quartulli
OpenVPN Inc.