Implement m_getm() which will perform an "all or nothing" mbuf + cluster

allocation, as required.

If m_getm() receives NULL as a first argument, then it allocates `len'
(second argument) bytes worth of mbufs + clusters and returns the chain
only if it was able to allocate everything.
If the first argument is non-NULL, then it should be an existing mbuf
chain (e.g. pre-allocated mbuf sitting on a ring, on some list, etc.) and
so it will allocate `len' bytes worth of clusters and mbufs, as needed,
and append them to the tail of the passed in chain, only if it was able
to allocate everything requested.

If allocation fails, only what was allocated by the routine will be freed,
and NULL will be returned.

Also, get rid of existing m_getm() in netncp code and replace calls to it
to calls to this new generic code.

Heavily Reviewed by: bp

1 files changed, 2 insertions, 27 deletions

diff --git a/sys/netncp/ncp_rq.c b/sys/netncp/ncp_rq.c
index e661f5e..dacdee0 100644
--- a/sys/netncp/ncp_rq.c
+++ b/sys/netncp/ncp_rq.c
@@ -46,8 +46,6 @@
 #include <netncp/ncp_ncp.h>
 #include <netncp/ncp_nls.h>
 
-static struct mbuf* m_getm(struct mbuf *top, int len);
-
 int
 ncp_rq_head(struct ncp_rq *rqp, u_int32_t ptype, u_int8_t fn,struct proc *p,
     struct ucred *cred)
@@ -98,29 +96,6 @@ ncp_rq_done(struct ncp_rq *rqp) {
 	return (0);
 }
 
-static struct mbuf*
-m_getm(struct mbuf *top, int len) {
-	int rest = len, mlen;
-	struct mbuf *m=0,*mp;
-	
-	mp = top;
-	while (rest > 0) {
-/*	NCPSDEBUG("%d\n",rest);*/
-		m = m_get(M_TRYWAIT, MT_DATA);
-		if (rest > MINCLSIZE) {
-			MCLGET(m,M_TRYWAIT);
-			mlen = ( (m->m_flags & M_EXT) == 0) ? MLEN : MCLBYTES;
-		} else { 
-			mlen = MLEN;
-		}
-		m->m_len = 0/*min(mlen,rest)*/;
-		mp->m_next = m;
-		mp = m;
-		rest -= mlen;
-	}
-	return top;
-}
-
 /*
  * Routines to fill the request
  */
@@ -182,7 +157,7 @@ ncp_rq_pathstring(struct ncp_rq *rqp, int size, char *name, struct ncp_nlstables
 		m->m_len += cplen;
 	}
 	if (size) {
-		m_getm(m, size);
+		m = m_getm(m, size, MT_DATA, M_TRYWAIT);
 		while (size > 0){
 			m = m->m_next;
 			cplen = min(size, M_TRAILINGSPACE(m));
@@ -215,7 +190,7 @@ ncp_rq_putanymem(struct ncp_rq *rqp, caddr_t source, int size, int type) {
 		m->m_len += cplen;
 	}
 	if (size) {
-		m_getm(m, size);
+		m = m_getm(m, size, MT_DATA, M_TRYWAIT);
 		while (size > 0){
 			m = m->m_next;
 			cplen = min(size, M_TRAILINGSPACE(m));