cleanups in m_pullup: remove unneeded length test, be careful

to leave offset pointing in current mbuf [cluster], don't go an extra turn
around the loop with a zero count

SCCS-vsn: sys/kern/uipc_mbuf.c 6.6

diff --git a/usr/src/sys/kern/uipc_mbuf.c b/usr/src/sys/kern/uipc_mbuf.c
index ca8d4af..691e346 100644 (file)
--- a/usr/src/sys/kern/uipc_mbuf.c
+++ b/usr/src/sys/kern/uipc_mbuf.c
@@ -3,7 +3,7 @@
  * All rights reserved.  The Berkeley software License Agreement
  * specifies the terms and conditions for redistribution.
  *
  * All rights reserved.  The Berkeley software License Agreement
  * specifies the terms and conditions for redistribution.
  *

- *     @(#)uipc_mbuf.c 6.5 (Berkeley) %G%
+ *     @(#)uipc_mbuf.c 6.6 (Berkeley) %G%

  */
 
 #include "../machine/pte.h"
  */
 
 #include "../machine/pte.h"


@@ -313,6 +313,13 @@ m_adj(mp, len)
        }
 }
 
        }
 }
 

+/*
+ * Rearange an mbuf chain so that len bytes are contiguous
+ * and in the data area of an mbuf (so that mtod and dtom
+ * will work for a structure of size len).
+ * Returns the resulting mbuf chain on success,
+ * frees it and returns null on failure.
+ */

 struct mbuf *
 m_pullup(m0, len)
        struct mbuf *m0;
 struct mbuf *
 m_pullup(m0, len)
        struct mbuf *m0;


@@ -329,19 +336,17 @@ m_pullup(m0, len)
                goto bad;
        m->m_len = 0;
        do {
                goto bad;
        m->m_len = 0;
        do {

-               count = MIN(MLEN - m->m_len, len);
-               if (count > n->m_len)
-                       count = n->m_len;
+               count = MIN(n->m_len, len);

                bcopy(mtod(n, caddr_t), mtod(m, caddr_t)+m->m_len,
                  (unsigned)count);
                len -= count;
                m->m_len += count;
                bcopy(mtod(n, caddr_t), mtod(m, caddr_t)+m->m_len,
                  (unsigned)count);
                len -= count;
                m->m_len += count;

-               n->m_off += count;

                n->m_len -= count;
                if (n->m_len)
                n->m_len -= count;
                if (n->m_len)

-                       break;
-               n = m_free(n);
-       } while (n);
+                       n->m_off += count;
+               else
+                       n = m_free(n);
+       } while (len && n);

        if (len) {
                (void) m_free(m);
                goto bad;
        if (len) {
                (void) m_free(m);
                goto bad;