[PATCH 5.15.y 1/3] inet: frags: add inet_frag_putn() helper

[Sasha Levin <sashal@kernel.org>]

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit ae2d90355aa5592b0e99c8bbb4c3fa1d8e205f1b ]

inet_frag_putn() can release multiple references
in one step.

Use it in inet_frags_free_cb().

Replace inet_frag_put(X) with inet_frag_putn(X, 1)

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250312082250.1803501-2-edumazet@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Stable-dep-of: e36ce6e78fe3 ("ip: orphan prefetched skbs before multicast forwarding")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 include/net/inet_frag.h                 | 4 ++--
 include/net/ipv6_frag.h                 | 3 ++-
 net/ieee802154/6lowpan/reassembly.c     | 7 ++++---
 net/ipv4/inet_fragment.c                | 3 +--
 net/ipv4/ip_fragment.c                  | 2 +-
 net/ipv6/netfilter/nf_conntrack_reasm.c | 3 ++-
 net/ipv6/reassembly.c                   | 4 ++--
 7 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/include/net/inet_frag.h b/include/net/inet_frag.h
index 63540be0fc34a..5c782c1feb5a1 100644
--- a/include/net/inet_frag.h
+++ b/include/net/inet_frag.h
@@ -136,9 +136,9 @@ struct inet_frag_queue *inet_frag_find(struct fqdir *fqdir, void *key);
 /* Free all skbs in the queue; return the sum of their truesizes. */
 unsigned int inet_frag_rbtree_purge(struct rb_root *root);
 
-static inline void inet_frag_put(struct inet_frag_queue *q)
+static inline void inet_frag_putn(struct inet_frag_queue *q, int refs)
 {
-	if (refcount_dec_and_test(&q->refcnt))
+	if (refs && refcount_sub_and_test(refs, &q->refcnt))
 		inet_frag_destroy(q);
 }
 
diff --git a/include/net/ipv6_frag.h b/include/net/ipv6_frag.h
index 0a4779175a523..3443c7905b785 100644
--- a/include/net/ipv6_frag.h
+++ b/include/net/ipv6_frag.h
@@ -65,6 +65,7 @@ ip6frag_expire_frag_queue(struct net *net, struct frag_queue *fq)
 {
 	struct net_device *dev = NULL;
 	struct sk_buff *head;
+	int refs = 1;
 
 	rcu_read_lock();
 	/* Paired with the WRITE_ONCE() in fqdir_pre_exit(). */
@@ -107,7 +108,7 @@ ip6frag_expire_frag_queue(struct net *net, struct frag_queue *fq)
 	spin_unlock(&fq->q.lock);
 out_rcu_unlock:
 	rcu_read_unlock();
-	inet_frag_put(&fq->q);
+	inet_frag_putn(&fq->q, refs);
 }
 
 /* Check if the upper layer header is truncated in the first fragment. */
diff --git a/net/ieee802154/6lowpan/reassembly.c b/net/ieee802154/6lowpan/reassembly.c
index be6f06adefe0a..f5b554894d024 100644
--- a/net/ieee802154/6lowpan/reassembly.c
+++ b/net/ieee802154/6lowpan/reassembly.c
@@ -45,6 +45,7 @@ static void lowpan_frag_expire(struct timer_list *t)
 {
 	struct inet_frag_queue *frag = from_timer(frag, t, timer);
 	struct frag_queue *fq;
+	int refs = 1;
 
 	fq = container_of(frag, struct frag_queue, q);
 
@@ -56,7 +57,7 @@ static void lowpan_frag_expire(struct timer_list *t)
 	inet_frag_kill(&fq->q);
 out:
 	spin_unlock(&fq->q.lock);
-	inet_frag_put(&fq->q);
+	inet_frag_putn(&fq->q, refs);
 }
 
 static inline struct lowpan_frag_queue *
@@ -301,13 +302,13 @@ int lowpan_frag_rcv(struct sk_buff *skb, u8 frag_type)
 
 	fq = fq_find(net, cb, &hdr.source, &hdr.dest);
 	if (fq != NULL) {
-		int ret;
+		int ret, refs = 1;
 
 		spin_lock(&fq->q.lock);
 		ret = lowpan_frag_queue(fq, skb, frag_type);
 		spin_unlock(&fq->q.lock);
 
-		inet_frag_put(&fq->q);
+		inet_frag_putn(&fq->q, refs);
 		return ret;
 	}
 
diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c
index 6e6b46ebfc407..4de79ee66a1cb 100644
--- a/net/ipv4/inet_fragment.c
+++ b/net/ipv4/inet_fragment.c
@@ -144,8 +144,7 @@ static void inet_frags_free_cb(void *ptr, void *arg)
 	}
 	spin_unlock_bh(&fq->lock);
 
-	if (refcount_sub_and_test(count, &fq->refcnt))
-		inet_frag_destroy(fq);
+	inet_frag_putn(fq, count);
 }
 
 static LLIST_HEAD(fqdir_free_list);
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index 23312d028af28..11dedc82b98da 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -107,7 +107,7 @@ static void ip4_frag_free(struct inet_frag_queue *q)
 
 static void ipq_put(struct ipq *ipq)
 {
-	inet_frag_put(&ipq->q);
+	inet_frag_putn(&ipq->q, 1);
 }
 
 /* Kill ipq entry. It is not destroyed immediately,
diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c
index d3b728771737a..dea2ed5f9f5aa 100644
--- a/net/ipv6/netfilter/nf_conntrack_reasm.c
+++ b/net/ipv6/netfilter/nf_conntrack_reasm.c
@@ -448,6 +448,7 @@ int nf_ct_frag6_gather(struct net *net, struct sk_buff *skb, u32 user)
 	struct frag_hdr *fhdr;
 	struct frag_queue *fq;
 	struct ipv6hdr *hdr;
+	int refs = 1;
 	u8 prevhdr;
 
 	/* Jumbo payload inhibits frag. header */
@@ -490,7 +491,7 @@ int nf_ct_frag6_gather(struct net *net, struct sk_buff *skb, u32 user)
 	}
 
 	spin_unlock_bh(&fq->q.lock);
-	inet_frag_put(&fq->q);
+	inet_frag_putn(&fq->q, refs);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(nf_ct_frag6_gather);
diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
index 6993675171556..31bfc7932378a 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -374,7 +374,7 @@ static int ipv6_frag_rcv(struct sk_buff *skb)
 	fq = fq_find(net, fhdr->identification, hdr, iif);
 	if (fq) {
 		u32 prob_offset = 0;
-		int ret;
+		int ret, refs = 1;
 
 		spin_lock(&fq->q.lock);
 
@@ -383,7 +383,7 @@ static int ipv6_frag_rcv(struct sk_buff *skb)
 				     &prob_offset);
 
 		spin_unlock(&fq->q.lock);
-		inet_frag_put(&fq->q);
+		inet_frag_putn(&fq->q, refs);
 		if (prob_offset) {
 			__IP6_INC_STATS(net, __in6_dev_get_safely(skb->dev),
 					IPSTATS_MIB_INHDRERRORS);
-- 
2.53.0