Module Name: src
Committed By: riastradh
Date: Wed Apr 12 06:48:08 UTC 2023
Modified Files:
src/sys/kern: uipc_mbuf.c
src/sys/sys: mbuf.h
Log Message:
mbuf(9): New m_get_n, m_gethdr_n.
m_get_n(how, type, alignbytes, nbytes) returns an mbuf with no packet
header having space for nbytes, with an internal buffer pointer
aligned by alignbytes (typically ETHER_ALIGN or similar, if not
zero).
m_gethdr_n(how, type, alignbytes, nbytes) does the same but for an
mbuf with a packet header.
These return NULL on failure, which can happen either:
(a) because how is M_DONTWAIT and allocating memory would sleep, or
(b) because alignbytes + nbytes > MCLBYTES.
On exit, m_len is set to nbytes, as is m_pkthdr.len for m_gethdr_n.
These should be used to systematically replace all calls to m_get,
m_gethdr, MGET, MGETHDR, and m_getcl. Most calls to m_clget and
MCLGET will probably evaporate as a consequence.
Proposed on tech-net last year:
https://mail-index.netbsd.org/tech-net/2022/07/16/msg008285.html
To generate a diff of this commit:
cvs rdiff -u -r1.250 -r1.251 src/sys/kern/uipc_mbuf.c
cvs rdiff -u -r1.237 -r1.238 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:1.250 src/sys/kern/uipc_mbuf.c:1.251
--- src/sys/kern/uipc_mbuf.c:1.250 Sat Apr 1 06:30:19 2023
+++ src/sys/kern/uipc_mbuf.c Wed Apr 12 06:48:08 2023
@@ -1,4 +1,4 @@
-/* $NetBSD: uipc_mbuf.c,v 1.250 2023/04/01 06:30:19 skrll Exp $ */
+/* $NetBSD: uipc_mbuf.c,v 1.251 2023/04/12 06:48:08 riastradh Exp $ */
/*
* Copyright (c) 1999, 2001, 2018 The NetBSD Foundation, Inc.
@@ -62,7 +62,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uipc_mbuf.c,v 1.250 2023/04/01 06:30:19 skrll Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uipc_mbuf.c,v 1.251 2023/04/12 06:48:08 riastradh Exp $");
#ifdef _KERNEL_OPT
#include "opt_mbuftrace.h"
@@ -587,6 +587,50 @@ m_gethdr(int how, int type)
return m;
}
+struct mbuf *
+m_get_n(int how, int type, size_t alignbytes, size_t nbytes)
+{
+ struct mbuf *m;
+
+ if (alignbytes > MCLBYTES || nbytes > MCLBYTES - alignbytes)
+ return NULL;
+ if ((m = m_get(how, type)) == NULL)
+ return NULL;
+ if (nbytes + alignbytes > MLEN) {
+ m_clget(m, how);
+ if ((m->m_flags & M_EXT) == 0) {
+ m_free(m);
+ return NULL;
+ }
+ }
+ m->m_len = alignbytes + nbytes;
+ m_adj(m, alignbytes);
+
+ return m;
+}
+
+struct mbuf *
+m_gethdr_n(int how, int type, size_t alignbytes, size_t nbytes)
+{
+ struct mbuf *m;
+
+ if (nbytes > MCLBYTES || nbytes > MCLBYTES - alignbytes)
+ return NULL;
+ if ((m = m_gethdr(how, type)) == NULL)
+ return NULL;
+ if (alignbytes + nbytes > MHLEN) {
+ m_clget(m, how);
+ if ((m->m_flags & M_EXT) == 0) {
+ m_free(m);
+ return NULL;
+ }
+ }
+ m->m_len = m->m_pkthdr.len = alignbytes + nbytes;
+ m_adj(m, alignbytes);
+
+ return m;
+}
+
void
m_clget(struct mbuf *m, int how)
{
Index: src/sys/sys/mbuf.h
diff -u src/sys/sys/mbuf.h:1.237 src/sys/sys/mbuf.h:1.238
--- src/sys/sys/mbuf.h:1.237 Fri Dec 16 08:42:55 2022
+++ src/sys/sys/mbuf.h Wed Apr 12 06:48:08 2023
@@ -1,4 +1,4 @@
-/* $NetBSD: mbuf.h,v 1.237 2022/12/16 08:42:55 msaitoh Exp $ */
+/* $NetBSD: mbuf.h,v 1.238 2023/04/12 06:48:08 riastradh Exp $ */
/*
* Copyright (c) 1996, 1997, 1999, 2001, 2007 The NetBSD Foundation, Inc.
@@ -740,6 +740,8 @@ struct mbuf *m_devget(char *, int, int,
struct mbuf *m_dup(struct mbuf *, int, int, int);
struct mbuf *m_get(int, int);
struct mbuf *m_gethdr(int, int);
+struct mbuf *m_get_n(int, int, size_t, size_t);
+struct mbuf *m_gethdr_n(int, int, size_t, size_t);
struct mbuf *m_prepend(struct mbuf *,int, int);
struct mbuf *m_pulldown(struct mbuf *, int, int, int *);
struct mbuf *m_pullup(struct mbuf *, int);
