inet: frags: add inet_frag_queue_flush()

Instead of exporting inet_frag_rbtree_purge() which requires that
caller takes care of memory accounting, add a new helper. We will
need to call it from a few places in the next patch.

Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20251207010942.1672972-3-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: kuba-moo

include/net/inet_frag.h

@@ -141,9 +141,8 @@ void inet_frag_kill(struct inet_frag_queue *q, int *refs);
 void inet_frag_destroy(struct inet_frag_queue *q);
 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,
-				    enum skb_drop_reason reason);
+void inet_frag_queue_flush(struct inet_frag_queue *q,
+			   enum skb_drop_reason reason);
 
 static inline void inet_frag_putn(struct inet_frag_queue *q, int refs)
 {

net/ipv4/inet_fragment.c

@@ -263,8 +263,8 @@ static void inet_frag_destroy_rcu(struct rcu_head *head)
 	kmem_cache_free(f->frags_cachep, q);
 }
 
-unsigned int inet_frag_rbtree_purge(struct rb_root *root,
-				    enum skb_drop_reason reason)
+static unsigned int
+inet_frag_rbtree_purge(struct rb_root *root, enum skb_drop_reason reason)
 {
 	struct rb_node *p = rb_first(root);
 	unsigned int sum = 0;
@@ -284,7 +284,16 @@ unsigned int inet_frag_rbtree_purge(struct rb_root *root,
 	}
 	return sum;
 }
-EXPORT_SYMBOL(inet_frag_rbtree_purge);
+
+void inet_frag_queue_flush(struct inet_frag_queue *q,
+			   enum skb_drop_reason reason)
+{
+	unsigned int sum;
+
+	sum = inet_frag_rbtree_purge(&q->rb_fragments, reason);
+	sub_frag_mem_limit(q->fqdir, sum);
+}
+EXPORT_SYMBOL(inet_frag_queue_flush);
 
 void inet_frag_destroy(struct inet_frag_queue *q)
 {

net/ipv4/ip_fragment.c

@@ -240,14 +240,10 @@ static int ip_frag_too_far(struct ipq *qp)
 
 static int ip_frag_reinit(struct ipq *qp)
 {
-	unsigned int sum_truesize = 0;
-
 	if (!mod_timer_pending(&qp->q.timer, jiffies + qp->q.fqdir->timeout))
 		return -ETIMEDOUT;
 
-	sum_truesize = inet_frag_rbtree_purge(&qp->q.rb_fragments,
-					      SKB_DROP_REASON_FRAG_TOO_FAR);
-	sub_frag_mem_limit(qp->q.fqdir, sum_truesize);
+	inet_frag_queue_flush(&qp->q, SKB_DROP_REASON_FRAG_TOO_FAR);
 
 	qp->q.flags = 0;
 	qp->q.len = 0;