add ml_filter and mq_filter functions to the mbuf list and queue apis.

this lets you run a filter function against each mbuf on a list or
queue. if the filter matches on an mbuf, it can return non-zero to
have ml_filter or mq_filter remove the mbuf and return it as part
of a chain of mbufs.

ok mpi@ claudio@ henning@ and s2k15 generally.

2 files changed, 48 insertions, 2 deletions

diff --git a/sys/kern/uipc_mbuf.c b/sys/kern/uipc_mbuf.c
index 1552168123e..b61159729f6 100644
--- a/sys/kern/uipc_mbuf.c
+++ b/sys/kern/uipc_mbuf.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uipc_mbuf.c,v 1.199 2014/12/11 19:21:57 tedu Exp $	*/
+/*	$OpenBSD: uipc_mbuf.c,v 1.200 2015/02/07 02:30:00 dlg Exp $	*/
 /*	$NetBSD: uipc_mbuf.c,v 1.15.4.1 1996/06/13 17:11:44 cgd Exp $	*/
 
 /*
@@ -1309,6 +1309,35 @@ ml_dechain(struct mbuf_list *ml)
 	return (m0);
 }
 
+struct mbuf *
+ml_filter(struct mbuf_list *ml,
+    int (*filter)(void *, const struct mbuf *), void *ctx)
+{
+	struct mbuf_list matches = MBUF_LIST_INITIALIZER();
+	struct mbuf *m, *n;
+	struct mbuf **mp;
+
+	mp = &ml->ml_head;
+
+	for (m = ml->ml_head; m != NULL; m = n) {
+		n = m->m_nextpkt;
+		if ((*filter)(ctx, m)) {
+			*mp = n;
+			ml_enqueue(&matches, m);
+		} else {
+			mp = &m->m_nextpkt;
+			ml->ml_tail = m;
+		}
+	}
+
+	/* fixup ml */
+	if (ml->ml_head == NULL)
+		ml->ml_tail = NULL;
+	ml->ml_len -= ml_len(&matches);
+
+	return (matches.ml_head); /* ml_dechain */
+}
+
 /*
  * mbuf queues
  */
@@ -1386,3 +1415,16 @@ mq_dechain(struct mbuf_queue *mq)
 
 	return (m0);
 }
+
+struct mbuf *
+mq_filter(struct mbuf_queue *mq,
+    int (*filter)(void *, const struct mbuf *), void *ctx)
+{
+	struct mbuf *m0;
+
+	mtx_enter(&mq->mq_mtx);
+	m0 = ml_filter(&mq->mq_list, filter, ctx);
+	mtx_leave(&mq->mq_mtx);
+
+	return (m0);
+}
diff --git a/sys/sys/mbuf.h b/sys/sys/mbuf.h
index f5136e5995e..bccdc0db655 100644
--- a/sys/sys/mbuf.h
+++ b/sys/sys/mbuf.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mbuf.h,v 1.184 2015/01/20 18:12:49 deraadt Exp $	*/
+/*	$OpenBSD: mbuf.h,v 1.185 2015/02/07 02:30:00 dlg Exp $	*/
 /*	$NetBSD: mbuf.h,v 1.19 1996/02/09 18:25:14 christos Exp $	*/
 
 /*
@@ -500,6 +500,8 @@ void			ml_init(struct mbuf_list *);
 void			ml_enqueue(struct mbuf_list *, struct mbuf *);
 struct mbuf *		ml_dequeue(struct mbuf_list *);
 struct mbuf *		ml_dechain(struct mbuf_list *);
+struct mbuf *		ml_filter(struct mbuf_list *,
+			    int (*)(void *, const struct mbuf *), void *);
 
 #define	ml_len(_ml)		((_ml)->ml_len)
 #define	ml_empty(_ml)		((_ml)->ml_len == 0)
@@ -527,6 +529,8 @@ struct mbuf *		mq_dequeue(struct mbuf_queue *);
 int			mq_enlist(struct mbuf_queue *, struct mbuf_list *);
 void			mq_delist(struct mbuf_queue *, struct mbuf_list *);
 struct mbuf *		mq_dechain(struct mbuf_queue *);
+struct mbuf *		mq_filter(struct mbuf_queue *,
+			    int (*)(void *, const struct mbuf *), void *);
 
 #define	mq_len(_mq)		ml_len(&(_mq)->mq_list)
 #define	mq_empty(_mq)		ml_empty(&(_mq)->mq_list)