[PATCH net v2 1/2] skbuff: skb_clone_sk_optional(): add function to always clone a skb and increase refcount on sk if valid
From: Oleksij Rempel <o.rempel@pengutronix.de>
Date: 2021-02-23 05:56:07
Also in:
linux-can, lkml, netdev
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
There already the function skb_clone_sk(), which clones the skb, but only if the sk is valid. There are several users in the networking stack, which always need a clone of a skb with the sk refcount incremented (but only if the sk is valid). This patch adds such a function. Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de> --- include/linux/skbuff.h | 1 + net/core/skbuff.c | 27 +++++++++++++++++++++++++++ 2 files changed, 28 insertions(+)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 6d0a33d1c0db..99d552017508 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h@@ -3874,6 +3874,7 @@ static inline void skb_metadata_clear(struct sk_buff *skb) skb_metadata_set(skb, 0); } +struct sk_buff *skb_clone_sk_optional(struct sk_buff *skb); struct sk_buff *skb_clone_sk(struct sk_buff *skb); #ifdef CONFIG_NETWORK_PHY_TIMESTAMPING
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 545a472273a5..97341f173fb0 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c@@ -4671,6 +4671,33 @@ struct sk_buff *sock_dequeue_err_skb(struct sock *sk) } EXPORT_SYMBOL(sock_dequeue_err_skb); +/** + * skb_clone_sk_optional - create clone of skb, and take reference to socket if + * socket is referenced in original skb + * @skb: the skb to clone + * + * This function always creates a clone of a buffer. If it that holds a valid + * reference on sk_refcnt this is increased. + */ +struct sk_buff *skb_clone_sk_optional(struct sk_buff *skb) +{ + struct sock *sk = skb->sk; + struct sk_buff *clone; + + clone = skb_clone(skb, GFP_ATOMIC); + if (!clone) + return NULL; + + if (!sk || !refcount_inc_not_zero(&sk->sk_refcnt)) + return clone; + + clone->sk = sk; + clone->destructor = sock_efree; + + return clone; +} +EXPORT_SYMBOL(skb_clone_sk_optional); + /** * skb_clone_sk - create clone of skb, and take reference to socket * @skb: the skb to clone
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2.29.2