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Date:      Sat, 10 Jan 2015 10:41:24 +0000 (UTC)
From:      Robert Watson <rwatson@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r276910 - in head/sys: kern sys
Message-ID:  <201501101041.t0AAfO3v063888@svn.freebsd.org>
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Author: rwatson
Date: Sat Jan 10 10:41:23 2015
New Revision: 276910
URL: https://svnweb.freebsd.org/changeset/base/276910

Log:
  Garbage collect m_copymdata(), an mbuf utility routine introduced
  in FreeBSD 7 that has not been used since.  It contains a number
  of unresolved bugs including an inverted bcopy() and incorrect
  handling of read-only mbufs using internal storage.  Removing this
  unused code is substantially essier than fixing it in order to
  update it to the coming mbuf world order -- but it can always be
  restored from revision history if it turns out to prove useful for
  future work.
  
  Pointed out by:	jmallett
  Sponsored by:	EMC / Isilon Storage Division

Modified:
  head/sys/kern/uipc_mbuf.c
  head/sys/sys/mbuf.h

Modified: head/sys/kern/uipc_mbuf.c
==============================================================================
--- head/sys/kern/uipc_mbuf.c	Sat Jan 10 10:16:22 2015	(r276909)
+++ head/sys/kern/uipc_mbuf.c	Sat Jan 10 10:41:23 2015	(r276910)
@@ -648,152 +648,6 @@ nospace:
 }
 
 /*
- * Returns mbuf chain with new head for the prepending case.
- * Copies from mbuf (chain) n from off for len to mbuf (chain) m
- * either prepending or appending the data.
- * The resulting mbuf (chain) m is fully writeable.
- * m is destination (is made writeable)
- * n is source, off is offset in source, len is len from offset
- * dir, 0 append, 1 prepend
- * how, wait or nowait
- */
-
-static int
-m_bcopyxxx(void *s, void *t, u_int len)
-{
-	bcopy(s, t, (size_t)len);
-	return 0;
-}
-
-struct mbuf *
-m_copymdata(struct mbuf *m, struct mbuf *n, int off, int len,
-    int prep, int how)
-{
-	struct mbuf *mm, *x, *z, *prev = NULL;
-	caddr_t p;
-	int i, nlen = 0;
-	caddr_t buf[MLEN];
-
-	KASSERT(m != NULL && n != NULL, ("m_copymdata, no target or source"));
-	KASSERT(off >= 0, ("m_copymdata, negative off %d", off));
-	KASSERT(len >= 0, ("m_copymdata, negative len %d", len));
-	KASSERT(prep == 0 || prep == 1, ("m_copymdata, unknown direction %d", prep));
-
-	mm = m;
-	if (!prep) {
-		while(mm->m_next) {
-			prev = mm;
-			mm = mm->m_next;
-		}
-	}
-	for (z = n; z != NULL; z = z->m_next)
-		nlen += z->m_len;
-	if (len == M_COPYALL)
-		len = nlen - off;
-	if (off + len > nlen || len < 1)
-		return NULL;
-
-	if (!M_WRITABLE(mm)) {
-		/* XXX: Use proper m_xxx function instead. */
-		x = m_getcl(how, MT_DATA, mm->m_flags);
-		if (x == NULL)
-			return NULL;
-		bcopy(mm->m_ext.ext_buf, x->m_ext.ext_buf, x->m_ext.ext_size);
-		p = x->m_ext.ext_buf + (mm->m_data - mm->m_ext.ext_buf);
-		x->m_data = p;
-		mm->m_next = NULL;
-		if (mm != m)
-			prev->m_next = x;
-		m_free(mm);
-		mm = x;
-	}
-
-	/*
-	 * Append/prepend the data.  Allocating mbufs as necessary.
-	 */
-	/* Shortcut if enough free space in first/last mbuf. */
-	if (!prep && M_TRAILINGSPACE(mm) >= len) {
-		m_apply(n, off, len, m_bcopyxxx, mtod(mm, caddr_t) +
-			 mm->m_len);
-		mm->m_len += len;
-		mm->m_pkthdr.len += len;
-		return m;
-	}
-	if (prep && M_LEADINGSPACE(mm) >= len) {
-		mm->m_data = mtod(mm, caddr_t) - len;
-		m_apply(n, off, len, m_bcopyxxx, mtod(mm, caddr_t));
-		mm->m_len += len;
-		mm->m_pkthdr.len += len;
-		return mm;
-	}
-
-	/* Expand first/last mbuf to cluster if possible. */
-	if (!prep && !(mm->m_flags & M_EXT) && len > M_TRAILINGSPACE(mm)) {
-		bcopy(mm->m_data, &buf, mm->m_len);
-		m_clget(mm, how);
-		if (!(mm->m_flags & M_EXT))
-			return NULL;
-		bcopy(&buf, mm->m_ext.ext_buf, mm->m_len);
-		mm->m_data = mm->m_ext.ext_buf;
-	}
-	if (prep && !(mm->m_flags & M_EXT) && len > M_LEADINGSPACE(mm)) {
-		bcopy(mm->m_data, &buf, mm->m_len);
-		m_clget(mm, how);
-		if (!(mm->m_flags & M_EXT))
-			return NULL;
-		bcopy(&buf, (caddr_t *)mm->m_ext.ext_buf +
-		    mm->m_ext.ext_size - mm->m_len, mm->m_len);
-		mm->m_data = (caddr_t)mm->m_ext.ext_buf +
-		    mm->m_ext.ext_size - mm->m_len;
-	}
-
-	/* Append/prepend as many mbuf (clusters) as necessary to fit len. */
-	if (!prep && len > M_TRAILINGSPACE(mm)) {
-		if (!m_getm(mm, len - M_TRAILINGSPACE(mm), how, MT_DATA))
-			return NULL;
-	}
-	if (prep && len > M_LEADINGSPACE(mm)) {
-		if (!(z = m_getm(NULL, len - M_LEADINGSPACE(mm), how, MT_DATA)))
-			return NULL;
-		i = 0;
-		for (x = z; x != NULL; x = x->m_next) {
-			i += x->m_flags & M_EXT ? x->m_ext.ext_size :
-			    (x->m_flags & M_PKTHDR ? MHLEN : MLEN);
-			if (!x->m_next)
-				break;
-		}
-		z->m_data += i - len;
-		m_move_pkthdr(mm, z);
-		x->m_next = mm;
-		mm = z;
-	}
-
-	/* Seek to start position in source mbuf. Optimization for long chains. */
-	while (off > 0) {
-		if (off < n->m_len)
-			break;
-		off -= n->m_len;
-		n = n->m_next;
-	}
-
-	/* Copy data into target mbuf. */
-	z = mm;
-	while (len > 0) {
-		KASSERT(z != NULL, ("m_copymdata, falling off target edge"));
-		i = M_TRAILINGSPACE(z);
-		m_apply(n, off, i, m_bcopyxxx, mtod(z, caddr_t) + z->m_len);
-		z->m_len += i;
-		/* fixup pkthdr.len if necessary */
-		if ((prep ? mm : m)->m_flags & M_PKTHDR)
-			(prep ? mm : m)->m_pkthdr.len += i;
-		off += i;
-		len -= i;
-		z = z->m_next;
-	}
-	return (prep ? mm : m);
-}
-
-/*
  * Copy an entire packet, including header (which must be present).
  * An optimization of the common case `m_copym(m, 0, M_COPYALL, how)'.
  * Note that the copy is read-only, because clusters are not copied,

Modified: head/sys/sys/mbuf.h
==============================================================================
--- head/sys/sys/mbuf.h	Sat Jan 10 10:16:22 2015	(r276909)
+++ head/sys/sys/mbuf.h	Sat Jan 10 10:41:23 2015	(r276910)
@@ -939,8 +939,6 @@ struct mbuf	*m_collapse(struct mbuf *, i
 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);
-struct mbuf	*m_copymdata(struct mbuf *, struct mbuf *,
-		    int, int, int, int);
 struct mbuf	*m_copypacket(struct mbuf *, int);
 void		 m_copy_pkthdr(struct mbuf *, struct mbuf *);
 struct mbuf	*m_copyup(struct mbuf *, int, int);

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