Module Name: src
Committed By: rmind
Date: Sat Jan 19 00:51:53 UTC 2013
Modified Files:
src/sys/kern: uipc_mbuf.c
src/sys/sys: mbuf.h
Log Message:
Add m_ensure_contig() routine, which is equivalent to m_pullup, but does not
destroy the mbuf chain on failure (it is kept valid).
To generate a diff of this commit:
cvs rdiff -u -r1.147 -r1.148 src/sys/kern/uipc_mbuf.c
cvs rdiff -u -r1.150 -r1.151 src/sys/sys/mbuf.h
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/uipc_mbuf.c
diff -u src/sys/kern/uipc_mbuf.c:1.147 src/sys/kern/uipc_mbuf.c:1.148
--- src/sys/kern/uipc_mbuf.c:1.147 Thu Oct 18 19:33:38 2012
+++ src/sys/kern/uipc_mbuf.c Sat Jan 19 00:51:52 2013
@@ -1,4 +1,4 @@
-/* $NetBSD: uipc_mbuf.c,v 1.147 2012/10/18 19:33:38 para Exp $ */
+/* $NetBSD: uipc_mbuf.c,v 1.148 2013/01/19 00:51:52 rmind Exp $ */
/*-
* Copyright (c) 1999, 2001 The NetBSD Foundation, Inc.
@@ -62,7 +62,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uipc_mbuf.c,v 1.147 2012/10/18 19:33:38 para Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uipc_mbuf.c,v 1.148 2013/01/19 00:51:52 rmind Exp $");
#include "opt_mbuftrace.h"
#include "opt_nmbclusters.h"
@@ -906,21 +906,18 @@ m_adj(struct mbuf *mp, int req_len)
}
/*
- * Rearrange 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.
- * If there is room, it will add up to max_protohdr-len extra bytes to the
- * contiguous region in an attempt to avoid being called next time.
+ * m_ensure_contig: rearrange an mbuf chain that given length of bytes
+ * would be contiguous and in the data area of an mbuf (therefore, mtod()
+ * would work for a structure of given length).
+ *
+ * => On success, returns true and the resulting mbuf chain; false otherwise.
+ * => The mbuf chain may change, but is always preserved valid.
*/
-int MPFail;
-
-struct mbuf *
-m_pullup(struct mbuf *n, int len)
+bool
+m_ensure_contig(struct mbuf **m0, int len)
{
- struct mbuf *m;
- int count;
- int space;
+ struct mbuf *n = *m0, *m;
+ size_t count, space;
/*
* If first mbuf has no cluster, and has room for len bytes
@@ -929,17 +926,20 @@ m_pullup(struct mbuf *n, int len)
*/
if ((n->m_flags & M_EXT) == 0 &&
n->m_data + len < &n->m_dat[MLEN] && n->m_next) {
- if (n->m_len >= len)
- return (n);
+ if (n->m_len >= len) {
+ return true;
+ }
m = n;
n = n->m_next;
len -= m->m_len;
} else {
- if (len > MHLEN)
- goto bad;
+ if (len > MHLEN) {
+ return false;
+ }
MGET(m, M_DONTWAIT, n->m_type);
- if (m == 0)
- goto bad;
+ if (m == NULL) {
+ return false;
+ }
MCLAIM(m, n->m_owner);
m->m_len = 0;
if (n->m_flags & M_PKTHDR) {
@@ -948,7 +948,7 @@ m_pullup(struct mbuf *n, int len)
}
space = &m->m_dat[MLEN] - (m->m_data + m->m_len);
do {
- count = min(min(max(len, max_protohdr), space), n->m_len);
+ count = MIN(MIN(MAX(len, max_protohdr), space), n->m_len);
memcpy(mtod(m, char *) + m->m_len, mtod(n, void *),
(unsigned)count);
len -= count;
@@ -960,16 +960,30 @@ m_pullup(struct mbuf *n, int len)
else
n = m_free(n);
} while (len > 0 && n);
- if (len > 0) {
- (void) m_free(m);
- goto bad;
- }
+
m->m_next = n;
- return (m);
-bad:
- m_freem(n);
- MPFail++;
- return (NULL);
+ *m0 = m;
+
+ return len <= 0;
+}
+
+/*
+ * m_pullup: same as m_ensure_contig(), but destroys mbuf chain on error.
+ */
+int MPFail;
+
+struct mbuf *
+m_pullup(struct mbuf *n, int len)
+{
+ struct mbuf *m = n;
+
+ if (!m_ensure_contig(&m, len)) {
+ KASSERT(m != NULL);
+ m_freem(m);
+ MPFail++;
+ m = NULL;
+ }
+ return m;
}
/*
Index: src/sys/sys/mbuf.h
diff -u src/sys/sys/mbuf.h:1.150 src/sys/sys/mbuf.h:1.151
--- src/sys/sys/mbuf.h:1.150 Thu Dec 27 14:41:10 2012
+++ src/sys/sys/mbuf.h Sat Jan 19 00:51:52 2013
@@ -1,4 +1,4 @@
-/* $NetBSD: mbuf.h,v 1.150 2012/12/27 14:41:10 christos Exp $ */
+/* $NetBSD: mbuf.h,v 1.151 2013/01/19 00:51:52 rmind Exp $ */
/*-
* Copyright (c) 1996, 1997, 1999, 2001, 2007 The NetBSD Foundation, Inc.
@@ -854,6 +854,8 @@ void m_ext_free(struct mbuf *);
char * m_mapin(struct mbuf *);
void m_move_pkthdr(struct mbuf *to, struct mbuf *from);
+bool m_ensure_contig(struct mbuf **, int);
+
/* Inline routines. */
static __inline u_int m_length(const struct mbuf *) __unused;
