[PATCH net-next 1/7] net: Add skb_dst_reset and skb_dst_restore
From: Stanislav Fomichev <sdf@fomichev.me>
Date: 2025-08-12 15:52:48
Also in:
linux-staging, lkml, netfilter-devel
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Going forward skb_dst_set will assert that skb dst_entry is empty during skb_dst_set to prevent potential leaks. There are few places that still manually manage dst_entry not using the helpers. Convert them to the following new helpers: - skb_dst_reset that resets dst_entry and returns previous dst_entry value - skb_dst_restore that restores dst_entry previously reset via skb_dst_restore Signed-off-by: Stanislav Fomichev <sdf@fomichev.me> --- include/linux/skbuff.h | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 14b923ddb6df..8240e0826204 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h@@ -1159,6 +1159,37 @@ static inline struct dst_entry *skb_dst(const struct sk_buff *skb) return (struct dst_entry *)(skb->_skb_refdst & SKB_DST_PTRMASK); } +/** + * 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. + * + * 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 + * @skb: buffer + */ +static inline void skb_dst_restore(struct sk_buff *skb, unsigned long refdst) +{ + skb->_skb_refdst = refdst; +} + /** * skb_dst_set - sets skb dst * @skb: buffer
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2.50.1