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Date: Wed, 5 Aug 2026 07:20:26 +0200
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Subject: Re: [PATCH net-next v14 0/5] tun/tap & vhost-net: apply qdisc
 backpressure on full ptr_ring to reduce TX drops
To: willemdebruijn.kernel@gmail.com, jasowangio@gmail.com, jasowang@redhat.com,
        andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com,
        kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, mst@redhat.com,
        eperezma@redhat.com, leiyang@redhat.com, stephen@networkplumber.org,
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References: <20260803183641.96882-1-simon.schippers@tu-dortmund.de>
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From: Simon Schippers <simon.schippers@tu-dortmund.de>
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On 8/3/26 20:36, Simon Schippers wrote:
> This patch series deals with tun/tap & vhost-net which drop incoming
> SKBs whenever their internal ptr_ring buffer is full. Instead, with this
> patch series, the associated netdev queue is stopped, but only when the
> new IFF_BACKPRESSURE flag is set and a qdisc is attached. Without the
> flag, or if no qdisc is present, the existing behavior is preserved. The
> XDP transmit path is not affected. This patch series touches tun/tap and
> vhost-net, as they share common logic and must be updated together.
> Modifying only one of them would break the other.
> 

Sashiko is happy now.

Gemini reports in patch 2:
"[Severity: Medium]
Will vhost-net bypass this wrapper and cause permanent TX queue stalls when
IFF_BACKPRESSURE is enabled?"
... but this is added in patch 3. It just cant cross-reference it.
So it is fine.