promote ath_defrag to m_collapse (and retire private+unused

m_collapse from cxgb)

Reviewed by:	pyun, jhb, kmacy
MFC after:	2 weeks

sys/dev/ath/if_ath.c

@@ -3891,90 +3891,6 @@ ath_tx_cleanup(struct ath_softc *sc)
 	ATH_TXQ_LOCK_DESTROY(&sc->sc_mcastq);
 }
 
-/*
- * Defragment an mbuf chain, returning at most maxfrags separate
- * mbufs+clusters.  If this is not possible NULL is returned and
- * the original mbuf chain is left in it's present (potentially
- * modified) state.  We use two techniques: collapsing consecutive
- * mbufs and replacing consecutive mbufs by a cluster.
- */
-static struct mbuf *
-ath_defrag(struct mbuf *m0, int how, int maxfrags)
-{
-	struct mbuf *m, *n, *n2, **prev;
-	u_int curfrags;
-
-	/*
-	 * Calculate the current number of frags.
-	 */
-	curfrags = 0;
-	for (m = m0; m != NULL; m = m->m_next)
-		curfrags++;
-	/*
-	 * First, try to collapse mbufs.  Note that we always collapse
-	 * towards the front so we don't need to deal with moving the
-	 * pkthdr.  This may be suboptimal if the first mbuf has much
-	 * less data than the following.
-	 */
-	m = m0;
-again:
-	for (;;) {
-		n = m->m_next;
-		if (n == NULL)
-			break;
-		if ((m->m_flags & M_RDONLY) == 0 &&
-		    n->m_len < M_TRAILINGSPACE(m)) {
-			bcopy(mtod(n, void *), mtod(m, char *) + m->m_len,
-				n->m_len);
-			m->m_len += n->m_len;
-			m->m_next = n->m_next;
-			m_free(n);
-			if (--curfrags <= maxfrags)
-				return m0;
-		} else
-			m = n;
-	}
-	KASSERT(maxfrags > 1,
-		("maxfrags %u, but normal collapse failed", maxfrags));
-	/*
-	 * Collapse consecutive mbufs to a cluster.
-	 */
-	prev = &m0->m_next;		/* NB: not the first mbuf */
-	while ((n = *prev) != NULL) {
-		if ((n2 = n->m_next) != NULL &&
-		    n->m_len + n2->m_len < MCLBYTES) {
-			m = m_getcl(how, MT_DATA, 0);
-			if (m == NULL)
-				goto bad;
-			bcopy(mtod(n, void *), mtod(m, void *), n->m_len);
-			bcopy(mtod(n2, void *), mtod(m, char *) + n->m_len,
-				n2->m_len);
-			m->m_len = n->m_len + n2->m_len;
-			m->m_next = n2->m_next;
-			*prev = m;
-			m_free(n);
-			m_free(n2);
-			if (--curfrags <= maxfrags)	/* +1 cl -2 mbufs */
-				return m0;
-			/*
-			 * Still not there, try the normal collapse
-			 * again before we allocate another cluster.
-			 */
-			goto again;
-		}
-		prev = &n->m_next;
-	}
-	/*
-	 * No place where we can collapse to a cluster; punt.
-	 * This can occur if, for example, you request 2 frags
-	 * but the packet requires that both be clusters (we
-	 * never reallocate the first mbuf to avoid moving the
-	 * packet header).
-	 */
-bad:
-	return NULL;
-}
-
 /*
  * Return h/w rate index for an IEEE rate (w/o basic rate bit).
  */
@@ -4033,7 +3949,7 @@ ath_tx_dmasetup(struct ath_softc *sc, struct ath_buf *bf, struct mbuf *m0)
 	 */
 	if (bf->bf_nseg > ATH_TXDESC) {		/* too many desc's, linearize */
 		sc->sc_stats.ast_tx_linear++;
-		m = ath_defrag(m0, M_DONTWAIT, ATH_TXDESC);
+		m = m_collapse(m0, M_DONTWAIT, ATH_TXDESC);
 		if (m == NULL) {
 			ath_freetx(m0);
 			sc->sc_stats.ast_tx_nombuf++;

sys/dev/cxgb/sys/mvec.h

@@ -114,7 +114,6 @@ void mi_init(void);
 void mi_deinit(void);
 
 int _m_explode(struct mbuf *);
-int _m_collapse(struct mbuf *, int maxbufs, struct mbuf **);
 void mb_free_vec(struct mbuf *m);
 
 static __inline void 
@@ -185,19 +184,6 @@ struct mbuf *mi_collapse_mbuf(struct mbuf_iovec *mi, struct mbuf *m);
 struct mbuf *mi_collapse_sge(struct mbuf_iovec *mi, bus_dma_segment_t *seg);
 void *mcl_alloc(int seg_count, int *type);
 
-static __inline int
-m_collapse(struct mbuf *m, int maxbufs, struct mbuf **mnew) 
-{
-#if (!defined(__sparc64__) && !defined(__sun4v__)) 	
-	if (m->m_next == NULL)
-#endif		
-	{
-		*mnew = m;
-		return (0);
-	}
-	return _m_collapse(m, maxbufs, mnew);
-} 
-
 void mb_free_ext_fast(struct mbuf_iovec *mi, int type, int idx);
 
 static __inline void

sys/kern/uipc_mbuf.c

@@ -1539,6 +1539,92 @@ nospace:
 	return (NULL);
 }
 
+/*
+ * Defragment an mbuf chain, returning at most maxfrags separate
+ * mbufs+clusters.  If this is not possible NULL is returned and
+ * the original mbuf chain is left in it's present (potentially
+ * modified) state.  We use two techniques: collapsing consecutive
+ * mbufs and replacing consecutive mbufs by a cluster.
+ *
+ * NB: this should really be named m_defrag but that name is taken
+ */
+struct mbuf *
+m_collapse(struct mbuf *m0, int how, int maxfrags)
+{
+	struct mbuf *m, *n, *n2, **prev;
+	u_int curfrags;
+
+	/*
+	 * Calculate the current number of frags.
+	 */
+	curfrags = 0;
+	for (m = m0; m != NULL; m = m->m_next)
+		curfrags++;
+	/*
+	 * First, try to collapse mbufs.  Note that we always collapse
+	 * towards the front so we don't need to deal with moving the
+	 * pkthdr.  This may be suboptimal if the first mbuf has much
+	 * less data than the following.
+	 */
+	m = m0;
+again:
+	for (;;) {
+		n = m->m_next;
+		if (n == NULL)
+			break;
+		if ((m->m_flags & M_RDONLY) == 0 &&
+		    n->m_len < M_TRAILINGSPACE(m)) {
+			bcopy(mtod(n, void *), mtod(m, char *) + m->m_len,
+				n->m_len);
+			m->m_len += n->m_len;
+			m->m_next = n->m_next;
+			m_free(n);
+			if (--curfrags <= maxfrags)
+				return m0;
+		} else
+			m = n;
+	}
+	KASSERT(maxfrags > 1,
+		("maxfrags %u, but normal collapse failed", maxfrags));
+	/*
+	 * Collapse consecutive mbufs to a cluster.
+	 */
+	prev = &m0->m_next;		/* NB: not the first mbuf */
+	while ((n = *prev) != NULL) {
+		if ((n2 = n->m_next) != NULL &&
+		    n->m_len + n2->m_len < MCLBYTES) {
+			m = m_getcl(how, MT_DATA, 0);
+			if (m == NULL)
+				goto bad;
+			bcopy(mtod(n, void *), mtod(m, void *), n->m_len);
+			bcopy(mtod(n2, void *), mtod(m, char *) + n->m_len,
+				n2->m_len);
+			m->m_len = n->m_len + n2->m_len;
+			m->m_next = n2->m_next;
+			*prev = m;
+			m_free(n);
+			m_free(n2);
+			if (--curfrags <= maxfrags)	/* +1 cl -2 mbufs */
+				return m0;
+			/*
+			 * Still not there, try the normal collapse
+			 * again before we allocate another cluster.
+			 */
+			goto again;
+		}
+		prev = &n->m_next;
+	}
+	/*
+	 * No place where we can collapse to a cluster; punt.
+	 * This can occur if, for example, you request 2 frags
+	 * but the packet requires that both be clusters (we
+	 * never reallocate the first mbuf to avoid moving the
+	 * packet header).
+	 */
+bad:
+	return NULL;
+}
+
 #ifdef MBUF_STRESS_TEST
 
 /*

sys/sys/mbuf.h

@@ -746,6 +746,7 @@ int		 m_append(struct mbuf *, int, c_caddr_t);
 void		 m_cat(struct mbuf *, struct mbuf *);
 void		 m_extadd(struct mbuf *, caddr_t, u_int,
 		    void (*)(void *, void *), void *, int, int);
+struct mbuf	*m_collapse(struct mbuf *, int, int);
 void		 m_copyback(struct mbuf *, int, int, c_caddr_t);
 void		 m_copydata(const struct mbuf *, int, int, caddr_t);
 struct mbuf	*m_copym(struct mbuf *, int, int, int);