From 73aa6a9430656ae5fc0c3edc2f264479fd9db2b5 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Sun, 1 Jan 1995 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1995-01-01

---
 port/portdat.h | 1 +
 port/proc.c    | 5 +++--
 port/qio.c     | 8 ++++++++
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/port/portdat.h b/port/portdat.h
index f7ba3f2af15a60e19276ed7708532161fcbbfe19..518de559a863001135a12ff69563e99231045424 100644
--- a/port/portdat.h
+++ b/port/portdat.h
@@ -132,6 +132,7 @@ struct Block
 	uchar*	wp;			/* first empty byte */
 	uchar*	lim;			/* 1 past the end of the buffer */
 	uchar*	base;			/* start of the buffer */
+	void	(*free)(Block*);
 	ulong	flag;
 };
 #define BLEN(s)	((s)->wp - (s)->rp)
diff --git a/port/proc.c b/port/proc.c
index f5967e0ab8275073df1a4bd49b7bb15e25f7d75c..d3ca0d6baeab6a3d78c158494fb975be5256ace3 100644
--- a/port/proc.c
+++ b/port/proc.c
@@ -216,9 +216,10 @@ loop:
 		 *  processor can run given affinity constraints
 		 */
 		for(rq = &runq[Nrq-1]; rq >= runq; rq--){
-			if(rq->head == 0)
+			p = rq->head;
+			if(p == 0)
 				continue;
-			for(p = rq->head; p; p = p->rnext){
+			for(; p; p = p->rnext){
 				if(p->mp == m || m->ticks - p->movetime > HZ/2)
 					goto found;
 			}
diff --git a/port/qio.c b/port/qio.c
index 7d8af518208df91c2226ca311a0250f00416712f..6d2eda17a0f971a3369c5396955669d01a3c0f8a 100644
--- a/port/qio.c
+++ b/port/qio.c
@@ -109,6 +109,14 @@ iallocb(int size)
 void
 freeb(Block *b)
 {
+	/*
+	 * drivers which perform non cache coherent DMA manage their
+	 * own buffer pools, so they provide their own free routines.
+	 */
+	if(b->free) {
+		b->free(b);
+		return;
+	}
 	if(b->flag & BINTR) {
 		ilock(&ialloc);
 		ialloc.bytes -= b->lim - b->base;