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note that m_get/MGET and friends, and M_PREPEND will never fail if M_WAIT 

is specified.  also note that MCLGET _can_.
This commit is contained in:
cgd 1996-06-10 23:55:39 +00:00
parent a15d9fa1d9
commit e7c37e7e8c
1 changed files with 8 additions and 4 deletions
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12
sys/sys/mbuf.h
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@ -1,4 +1,4 @@
/* $NetBSD: mbuf.h,v 1.20 1996/06/10 12:51:21 cgd Exp $ */
/* $NetBSD: mbuf.h,v 1.21 1996/06/10 23:55:39 cgd Exp $ */
/*
* Copyright (c) 1982, 1986, 1988, 1993
@ -162,6 +162,9 @@ struct mbuf {
* MGETHDR(struct mbuf *m, int how, int type)
* allocates an mbuf and initializes it to contain a packet header
* and internal data.
*
* If 'how' is M_WAIT, these macros (and the corresponding functions)
* are guaranteed to return successfully.
*/
#define MGET(m, how, type) { \
MALLOC((m), struct mbuf *, MSIZE, mbtypes[type], (how)); \
@ -192,8 +195,8 @@ struct mbuf {
/*
* Mbuf cluster macros.
* MCLALLOC(caddr_t p, int how) allocates an mbuf cluster.
* MCLGET adds such clusters to a normal mbuf;
* the flag M_EXT is set upon success.
* MCLGET adds such clusters to a normal mbuf; the flag M_EXT is
* set upon success. (Note that MCLGET with M_WAIT _MAY_ fail!)
* MCLFREE releases a reference to a cluster allocated by MCLALLOC,
* freeing the cluster if the reference count has reached 0.
*
@ -310,7 +313,8 @@ union mcluster {
* Arrange to prepend space of size plen to mbuf m.
* If a new mbuf must be allocated, how specifies whether to wait.
* If how is M_DONTWAIT and allocation fails, the original mbuf chain
* is freed and m is set to NULL.
* is freed and m is set to NULL. If how is M_WAIT, this will never
* fail.
*/
#define M_PREPEND(m, plen, how) { \
if (M_LEADINGSPACE(m) >= (plen)) { \