From 8fa17e17bf0e835e7745d6546cc520d1da43f3bb Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Thu, 21 Dec 2000 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 2000-12-21

---
 ip/devip.c | 18 ++++++++++++++----
 ip/tcp.c   | 41 +++++++++++++++++++++++++----------------
 pc/apm.c   |  1 +
 pc/fns.h   |  4 +++-
 pc/l.s     |  8 ++++++++
 5 files changed, 51 insertions(+), 21 deletions(-)

diff --git a/ip/devip.c b/ip/devip.c
index a62b266e71476efbda0bdc0dd161dce38ecb19f2..b6418e33e7b034e607e628e0ad44e247719d1242 100644
--- a/ip/devip.c
+++ b/ip/devip.c
@@ -799,11 +799,16 @@ connectctlmsg(Proto *x, Conv *c, Cmdbuf *cb)
 	p = x->connect(c, cb->f, cb->nf);
 	if(p != nil)
 		error(p);
-	qunlock(c);
 
+	qunlock(c);
+	if(waserror()){
+		qlock(c);
+		nexterror();
+	}
 	sleep(&c->cr, connected, c);
-
 	qlock(c);
+	poperror();
+
 	if(c->cerr[0] != '\0')
 		error(c->cerr);
 }
@@ -846,11 +851,16 @@ announcectlmsg(Proto *x, Conv *c, Cmdbuf *cb)
 	p = x->announce(c, cb->f, cb->nf);
 	if(p != nil)
 		error(p);
-	qunlock(c);
 
+	qunlock(c);
+	if(waserror()){
+		qlock(c);
+		nexterror();
+	}
 	sleep(&c->cr, announced, c);
-
 	qlock(c);
+	poperror();
+
 	if(c->cerr[0] != '\0')
 		error(c->cerr);
 }
diff --git a/ip/tcp.c b/ip/tcp.c
index 62dcf35cd1c213e3319b3f2aa98ea8ac01d410ad..9d514994bcb8422255814ed6d6baad818c342548 100644
--- a/ip/tcp.c
+++ b/ip/tcp.c
@@ -1649,7 +1649,9 @@ raise:
 }
 
 /*
- *  always enters and exits with the tcb locked
+ *  always enters and exits with the s locked.  We drop
+ *  the lock to ipoput the packet so some care has to be
+ *  taken by callers.
  */
 void
 tcpoutput(Conv *s)
@@ -1667,22 +1669,22 @@ tcpoutput(Conv *s)
 	f = s->p->f;
 	tpriv = s->p->priv;
 
-	tcb = (Tcpctl*)s->ptcl;
-
-	switch(tcb->state) {
-	case Listen:
-	case Closed:
-	case Finwait2:
-		return;
-	}
-
-	/* force an ack when a window has opened up */
-	if(tcb->rcv.blocked && tcb->rcv.wnd > 0){
-		tcb->rcv.blocked = 0;
-		tcb->flags |= FORCE;
-	}
-
 	for(msgs = 0; msgs < 100; msgs++) {
+		tcb = (Tcpctl*)s->ptcl;
+	
+		switch(tcb->state) {
+		case Listen:
+		case Closed:
+		case Finwait2:
+			return;
+		}
+	
+		/* force an ack when a window has opened up */
+		if(tcb->rcv.blocked && tcb->rcv.wnd > 0){
+			tcb->rcv.blocked = 0;
+			tcb->flags |= FORCE;
+		}
+	
 		sndcnt = tcb->sndcnt;
 		sent = tcb->snd.ptr - tcb->snd.una;
 
@@ -1850,7 +1852,14 @@ tcpoutput(Conv *s)
 		tpriv->stats[OutSegs]++;
 		if(tcb->kacounter > 0)
 			tcpgo(tpriv, &tcb->katimer);
+		qunlock(s);
+		if(waserror()){
+			qlock(s);
+			nexterror();
+		}
 		ipoput(f, hbp, 0, s->ttl, s->tos);
+		qlock(s);
+		poperror();
 	}
 }
 
diff --git a/pc/apm.c b/pc/apm.c
index 3e5797a99d17dd3a5d36aed6e78b507848533f00..01e83d5d58fcdc26913dc274f5e8d3321e6efce7 100644
--- a/pc/apm.c
+++ b/pc/apm.c
@@ -162,6 +162,7 @@ apmlink(void)
 	loadgdt();
 
 	addarchfile("apm", 0660, apmread, apmwrite);
+	doze = halt;
 
 print("apm0: configured cbase %.8lux off %.8lux\n", ax<<4, ebx);
 
diff --git a/pc/fns.h b/pc/fns.h
index da5cee1d332cfe1e787f0a8b8f416ce8c0023eb9..0729055afd38c312f500ae2cce542d4d6bf3c597 100644
--- a/pc/fns.h
+++ b/pc/fns.h
@@ -25,6 +25,7 @@ int	dmadone(int);
 void	dmaend(int);
 int	dmainit(int, int);
 long	dmasetup(int, void*, long, int);
+void	(*doze)(void);
 #define	evenaddr(x)				/* x86 doesn't care */
 void	fpenv(FPsave*);
 void	fpinit(void);
@@ -38,6 +39,7 @@ ulong	getcr3(void);
 ulong	getcr4(void);
 char*	getconf(char*);
 int	havecycintr(void);
+void	halt(void);	/* x86 HLT */
 int	i8042auxcmd(int);
 void	i8042auxenable(void (*)(int, int));
 void	i8042reset(void);
@@ -47,7 +49,7 @@ uvlong	i8253read(uvlong*);
 void	i8259init(void);
 int	i8259enable(Vctl*);
 void	idle(void);
-#define	idlehands()			/* nothing to do in the runproc */
+#define	idlehands()		if(doze==0);else doze()	/* nothing to do in the runproc */
 int	inb(int);
 void	insb(int, void*, int);
 ushort	ins(int);
diff --git a/pc/l.s b/pc/l.s
index c83941e7679a707dbe45567fa93eb77445f48f15..42478b685e855fa70e5baed09f13533856652009 100644
--- a/pc/l.s
+++ b/pc/l.s
@@ -12,6 +12,7 @@
 #define WRMSR		BYTE $0x0F; BYTE $0x30	/* WRMSR, argument in AX/DX (lo/hi) */
 #define RDMSR		BYTE $0x0F; BYTE $0x32	/* RDMSR, result in AX/DX (lo/hi) */
 #define WBINVD		BYTE $0x0F; BYTE $0x09
+#define HLT		BYTE $0xF4
 
 /*
  * Macros for calculating offsets within the page directory base
@@ -504,6 +505,13 @@ TEXT setlabel(SB), $0
 	MOVL	$0, AX				/* return 0 */
 	RET
 
+/*
+ * Attempt at power saving. -rsc
+ */
+TEXT halt(SB), $0
+	HLT
+	RET
+
 /*
  * Interrupt/exception handling.
  * Each entry in the vector table calls either _strayintr or _strayintrx depending