Michael S. Tsirkin wrote: > On Tue, Sep 02, 2025 at 10:09:55AM +0200, Simon Schippers wrote: >> The netdev queue is stopped in tun_net_xmit after inserting an SKB into >> the ring buffer if the ring buffer became full because of that. If the >> insertion into the ptr_ring fails, the netdev queue is also stopped and >> the SKB is dropped. However, this never happened in my testing. To ensure >> that the ptr_ring change is available to the consumer before the netdev >> queue stop, an smp_wmb() is used. > > I think the stop -> wake bounce involves enough barriers already, > no need for us to get cute. > Yes, you and Jason are correct, it seems to be unnecessary. I just removed the barriers, and it tests fine!
