kenrel: simplify image cache by use of ccloseq()

sys/src/9/port/chan.c

@@ -14,7 +14,7 @@ enum
 	PATHMSLOP	= 20,
 };
 
-struct
+static struct Chanalloc
 {
 	Lock;
 	int	fid;
@@ -223,8 +223,10 @@ newchan(void)
 
 	lock(&chanalloc);
 	c = chanalloc.free;
-	if(c != 0)
+	if(c != 0){
 		chanalloc.free = c->next;
+		c->next = 0;
+	}
 	unlock(&chanalloc);
 
 	if(c == nil){
@@ -532,7 +534,7 @@ closechanq(Chan *c)
 	clunkq.tail = c;
 	unlock(&clunkq.l);
 
-	if(canqlock(&clunkq.q)){
+	if(up != 0 && palloc.Lock.p != up && canqlock(&clunkq.q)){
 		c = up->dot;
 		up->dot = nil;
 		kproc("closeproc", closeproc, nil);

sys/src/9/port/segment.c

@@ -6,7 +6,6 @@
 #include	"../port/error.h"
 
 static void	imagereclaim(void);
-static void	imagechanreclaim(void);
 
 #include "io.h"
 
@@ -21,7 +20,6 @@ static Physseg physseg[10] = {
 
 static Lock physseglock;
 
-#define NFREECHAN	64
 #define IHASHSIZE	64
 #define ihash(s)	imagealloc.hash[s%IHASHSIZE]
 static struct Imagealloc
@@ -30,11 +28,6 @@ static struct Imagealloc
 	Image	*free;
 	Image	*hash[IHASHSIZE];
 	QLock	ireclaim;	/* mutex on reclaiming free images */
-
-	Chan	**freechan;	/* free image channels */
-	int	nfreechan;	/* number of free channels */
-	int	szfreechan;	/* size of freechan array */
-	QLock	fcreclaim;	/* mutex on reclaiming free channels */
 }imagealloc;
 
 Segment* (*_globalsegattach)(Proc*, char*);
@@ -51,10 +44,6 @@ initseg(void)
 	for(i = imagealloc.free; i < ie; i++)
 		i->next = i+1;
 	i->next = 0;
-	imagealloc.freechan = malloc(NFREECHAN * sizeof(Chan*));
-	if(imagealloc.freechan == nil)
-		panic("initseg: no memory for Chan");
-	imagealloc.szfreechan = NFREECHAN;
 }
 
 Segment *
@@ -249,10 +238,6 @@ attachimage(int type, Chan *c, ulong base, ulong len)
 {
 	Image *i, **l;
 
-	/* reclaim any free channels from reclaimed segments */
-	if(imagealloc.nfreechan)
-		imagechanreclaim();
-
 	lock(&imagealloc);
 
 	/*
@@ -362,41 +347,11 @@ imagereclaim(void)
 	qunlock(&imagealloc.ireclaim);
 }
 
-/*
- *  since close can block, this has to be called outside of
- *  spin locks.
- */
-static void
-imagechanreclaim(void)
-{
-	Chan *c;
-
-	/* Somebody is already cleaning the image chans */
-	if(!canqlock(&imagealloc.fcreclaim))
-		return;
-
-	/*
-	 * We don't have to recheck that nfreechan > 0 after we
-	 * acquire the lock, because we're the only ones who decrement 
-	 * it (the other lock contender increments it), and there's only
-	 * one of us thanks to the qlock above.
-	 */
-	while(imagealloc.nfreechan > 0){
-		lock(&imagealloc);
-		imagealloc.nfreechan--;
-		c = imagealloc.freechan[imagealloc.nfreechan];
-		unlock(&imagealloc);
-		cclose(c);
-	}
-
-	qunlock(&imagealloc.fcreclaim);
-}
-
 void
 putimage(Image *i)
 {
-	Chan *c, **cp;
 	Image *f, **l;
+	Chan *c;
 
 	if(i->notext)
 		return;
@@ -419,20 +374,9 @@ putimage(Image *i)
 
 		i->next = imagealloc.free;
 		imagealloc.free = i;
-
-		/* defer freeing channel till we're out of spin lock's */
-		if(imagealloc.nfreechan == imagealloc.szfreechan){
-			imagealloc.szfreechan += NFREECHAN;
-			cp = malloc(imagealloc.szfreechan*sizeof(Chan*));
-			if(cp == nil)
-				panic("putimage");
-			memmove(cp, imagealloc.freechan, imagealloc.nfreechan*sizeof(Chan*));
-			free(imagealloc.freechan);
-			imagealloc.freechan = cp;
-		}
-		imagealloc.freechan[imagealloc.nfreechan++] = c;
 		unlock(&imagealloc);
 
+		ccloseq(c);	/* does not block */
 		return;
 	}
 	unlock(i);