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Date: Wed, 13 Aug 2025 17:57:40 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: Stanislav Fomichev <sdf@fomichev.me>
Cc: netdev@vger.kernel.org, davem@davemloft.net, edumazet@google.com,
 pabeni@redhat.com, ayush.sawal@chelsio.com, andrew+netdev@lunn.ch,
 gregkh@linuxfoundation.org, horms@kernel.org, dsahern@kernel.org,
 pablo@netfilter.org, kadlec@netfilter.org, steffen.klassert@secunet.com,
 mhal@rbox.co, abhishektamboli9@gmail.com, linux-kernel@vger.kernel.org,
 linux-staging@lists.linux.dev, netfilter-devel@vger.kernel.org,
 coreteam@netfilter.org, herbert@gondor.apana.org.au
Subject: Re: [PATCH net-next 1/7] net: Add skb_dst_reset and skb_dst_restore
Message-ID: <20250813175740.4c24e747@kernel.org>
In-Reply-To: <20250812155245.507012-2-sdf@fomichev.me>
References: <20250812155245.507012-1-sdf@fomichev.me>
	<20250812155245.507012-2-sdf@fomichev.me>
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On Tue, 12 Aug 2025 08:52:39 -0700 Stanislav Fomichev wrote:
> +/**
> + * skb_dst_reset() - return current dst_entry value and clear it
> + * @skb: buffer
> + *
> + * Resets skb dst_entry without adjusting its reference count. Useful in
> + * cases where dst_entry needs to be temporarily reset and restored.
> + * Note that the returned value cannot be used directly because it
> + * might contain SKB_DST_NOREF bit.
> + *
> + * When in doubt, prefer skb_dst_drop() over skb_dst_reset() to correctly
> + * handle dst_entry reference counting.

thoughts on prefixing these two new helpers with __ to hint that
they are low level and best avoided?

> + *
> + * Returns: original skb dst_entry.
> + */
> +static inline unsigned long skb_dst_reset(struct sk_buff *skb)
> +{
> +	unsigned long refdst = skb->_skb_refdst;
> +
> +	skb->_skb_refdst = 0;
> +	return refdst;
> +}
> +
> +/**
> + * skb_dst_restore() - restore skb dst_entry saved via skb_dst_reset

saved -> removed ?
Also I think for better kdoc linking it's good to add () after function
names

> + * @skb: buffer

kdoc missing for refdst

> + */
> +static inline void skb_dst_restore(struct sk_buff *skb, unsigned long refdst)
> +{
> +	skb->_skb_refdst = refdst;