From 71e175c5795e7df54e3a73d156fe5dfbeff1b8a3 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Sat, 22 Aug 1992 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1992-08-22

---
 port/segment.c   |  3 +--
 port/tcpoutput.c | 21 ++++++---------------
 power/fptrap.c   |  6 +++---
 3 files changed, 10 insertions(+), 20 deletions(-)

diff --git a/port/segment.c b/port/segment.c
index c5c1f11dbcd1d918d50cb3a864d1bc885f0f8772..46f82ac7be74879671fa6247a075184057df6e7f 100644
--- a/port/segment.c
+++ b/port/segment.c
@@ -259,8 +259,7 @@ imagereclaim(void)
 
 	lock(&palloc);
 	for(p = palloc.head; p; p = p->next) {
-		if(p->image && p->ref == 0 && p->image != &swapimage) {
-			lock(p);
+		if(p->image && p->ref == 0 && p->image != &swapimage && canlock(p)) {
 			if(p->ref == 0)
 				uncachepage(p);
 			unlock(p);
diff --git a/port/tcpoutput.c b/port/tcpoutput.c
index 4388b1b2cc42caa75acb37cb8a295d1aec015ff5..4dbb3cd9a9e64158b2d893cada10c9c2777b18d2 100644
--- a/port/tcpoutput.c
+++ b/port/tcpoutput.c
@@ -94,11 +94,7 @@ tcp_output(Ipconv *s)
 		seg.ack = tcb->last_ack = tcb->rcv.nxt;
 		seg.wnd = tcb->rcv.wnd;
 
-		/* Now try to extract some data from the send queue.
-		 * Since SYN and FIN occupy sequence space and are reflected
-		 * in sndcnt but don't actually sit in the send queue,
-		 * dupb will return one less than dsize if a FIN needs to be sent.
-		 */
+		/* Pull out data to send */
 		dbp = 0;
 		if(dsize != 0){
 			if(dupb(&dbp, sndq, sent, dsize) != dsize) {
@@ -111,19 +107,14 @@ tcp_output(Ipconv *s)
 		if(sent+dsize == qlen)
 			seg.flags |= PSH;
 
-		/* If this transmission includes previously transmitted data,
-		 * snd.nxt will already be past snd.ptr. In this case,
-		 * compute the amount of retransmitted data and keep score
-		 */
+		/*
+		 * keep track of balance of resent data */
 		if(tcb->snd.ptr < tcb->snd.nxt)
 			tcb->resent += MIN((int)tcb->snd.nxt - (int)tcb->snd.ptr,(int)ssize);
 
 		tcb->snd.ptr += ssize;
 
-		/* If this is the first transmission of a range of sequence
-		 * numbers, record it so we'll accept acknowledgments
-		 * for it later
-		 */
+		/* Pull up the send pointer so we can accept acks for this window */
 		if(seq_gt(tcb->snd.ptr,tcb->snd.nxt))
 			tcb->snd.nxt = tcb->snd.ptr;
 
@@ -139,8 +130,8 @@ tcp_output(Ipconv *s)
 			return;
 		}
 
-		/* If we're sending some data or flags, start retransmission
-		 * and round trip timers if they aren't already running.
+		/* Start the transmission timers if there is new data and we
+		 * expect acknowledges
 		 */
 		if(ssize != 0){
 			tcb->timer.start = backoff(tcb->backoff) *
diff --git a/power/fptrap.c b/power/fptrap.c
index 7b8ff2e487e1d0e90e21c8626879ee6b62c4c7a6..efa8944bf974fc60f96d02d35cce3b9829e21880 100644
--- a/power/fptrap.c
+++ b/power/fptrap.c
@@ -47,8 +47,9 @@ fptrap(Ureg *ur, ulong fcr31)
 		}else
 			ur->pc += 4;
 		u->fpsave.fpstatus = fcr31 & ~(1<<17);
+		return 1;
 	}
-	return 1;
+	return 0;
 }
 
 static void
@@ -158,8 +159,7 @@ fpunimp(ulong iw)
 		sd = ss;
 		break;
 
-	default:
-		/* shouldn't get here */
+	default:	/* probably a compare */
 		return 0;
 	}
 	if(ed <= -(maxe-4)){	/* guess: underflow */