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Message-ID: <c908ce17-b2e9-472e-935c-f5133ddb9007@kernel.org>
Date: Mon, 7 Apr 2025 17:02:22 -0600
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Subject: Re: [RFC PATCH net-next] veth: apply qdisc backpressure on full
 ptr_ring to reduce TX drops
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To: =?UTF-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= <toke@redhat.com>,
 Jesper Dangaard Brouer <hawk@kernel.org>, netdev@vger.kernel.org,
 Jakub Kicinski <kuba@kernel.org>
Cc: bpf@vger.kernel.org, tom@herbertland.com,
 Eric Dumazet <eric.dumazet@gmail.com>, "David S. Miller"
 <davem@davemloft.net>, Paolo Abeni <pabeni@redhat.com>,
 kernel-team@cloudflare.com
References: <174377814192.3376479.16481605648460889310.stgit@firesoul>
 <87a58sxrhn.fsf@toke.dk>
From: David Ahern <dsahern@kernel.org>
In-Reply-To: <87a58sxrhn.fsf@toke.dk>
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On 4/7/25 3:15 AM, Toke Høiland-Jørgensen wrote:
>> +static inline bool txq_has_qdisc(struct netdev_queue *txq)
>> +{
>> +	struct Qdisc *q;
>> +
>> +	q = rcu_dereference(txq->qdisc);
>> +	if (q->enqueue)
>> +		return true;
>> +	else
>> +		return false;
>> +}
> 
> This seems like a pretty ugly layering violation, inspecting the qdisc
> like this in the driver?

vrf driver has something very similar - been there since March 2017.