Allow drivers to free an mbuf without having the mbuf be touched if

the driver has already freed any attached tags

Approved by: re(gnn)

2 files changed, 15 insertions, 2 deletions

diff --git a/sys/kern/kern_mbuf.c b/sys/kern/kern_mbuf.c
index 8023920..a5e1348 100644
--- a/sys/kern/kern_mbuf.c
+++ b/sys/kern/kern_mbuf.c
@@ -339,9 +339,12 @@ static void
 mb_dtor_mbuf(void *mem, int size, void *arg)
 {
 	struct mbuf *m;
+	unsigned long flags; 
 
 	m = (struct mbuf *)mem;
-	if ((m->m_flags & M_PKTHDR) != 0)
+	flags = (unsigned long)arg;
+	
+	if ((flags & MB_NOTAGS) == 0 && (m->m_flags & M_PKTHDR) != 0)
 		m_tag_delete_chain(m, NULL);
 	KASSERT((m->m_flags & M_EXT) == 0, ("%s: M_EXT set", __func__));
 #ifdef INVARIANTS
@@ -527,7 +530,7 @@ mb_ctor_pack(void *mem, int size, void *arg, int how)
 	m->m_len = 0;
 	m->m_flags = (flags | M_EXT);
 	m->m_type = type;
-
+	    
 	if (flags & M_PKTHDR) {
 		m->m_pkthdr.rcvif = NULL;
 		m->m_pkthdr.len = 0;
diff --git a/sys/sys/mbuf.h b/sys/sys/mbuf.h
index bf7c073..dc05c78 100644
--- a/sys/sys/mbuf.h
+++ b/sys/sys/mbuf.h
@@ -254,6 +254,8 @@ struct mbuf {
 #define	MT_NOINIT	255	/* Not a type but a flag to allocate
 				   a non-initialized mbuf */
 
+#define MB_NOTAGS	0x1UL	/* no tags attached to mbuf */
+
 /*
  * General mbuf allocator statistics structure.
  *
@@ -490,6 +492,14 @@ m_getjcl(int how, short type, int flags, int size)
 	return (m);
 }
 
+static __inline void
+m_free_fast(struct mbuf *m)
+{
+	KASSERT(SLIST_EMPTY(&m->m_pkthdr.tags), ("doing fast free of mbuf with tags"));
+
+	uma_zfree_arg(zone_mbuf, m, (void *)MB_NOTAGS);
+}
+
 static __inline struct mbuf *
 m_free(struct mbuf *m)
 {