revert some code that appears to be causing crashes

git-svn-id: http://svn.digium.com/svn/zaptel/branches/1.2@2078 5390a7c7-147a-4af0-8ec9-7488f05a26cb

1 files changed, 45 insertions, 40 deletions

diff --git a/zttranscode.c b/zttranscode.c
index aad71cc..39e84ae 100644
--- a/zttranscode.c
+++ b/zttranscode.c
@@ -47,7 +47,7 @@
 #endif
 
 static int debug = 0;
-static LIST_HEAD(trans);
+static struct zt_transcoder *trans;
 static spinlock_t translock = SPIN_LOCK_UNLOCKED;
 
 EXPORT_SYMBOL(zt_transcoder_register);
@@ -68,12 +68,11 @@ struct zt_transcoder *zt_transcoder_alloc(int numchans)
 	memset(ztc, 0, size);
 	strcpy(ztc->name, "<unspecified>");
 	ztc->numchannels = numchans;
-	INIT_LIST_HEAD(&ztc->list);
 	for (x=0;x<ztc->numchannels;x++) {
 		init_waitqueue_head(&ztc->channels[x].ready);
 		ztc->channels[x].parent = ztc;
 		ztc->channels[x].offset = x;
-		ztc->channels[x].chan_built = 0;
+		ztc->channels[x].flags.chan_built = 0;
 		ztc->channels[x].built_fmts = 0;
 	}
 
@@ -104,50 +103,58 @@ void zt_transcoder_free(struct zt_transcoder *ztc)
 	kfree(ztc);
 }
 
-int zt_transcoder_register(struct zt_transcoder *tc, struct module *owner)
+/* Register a transcoder */
+int zt_transcoder_register(struct zt_transcoder *tc)
 {
 	struct zt_transcoder *cur;
+	int res = -EBUSY;
 
 	spin_lock(&translock);
-	list_for_each_entry(cur, &trans, list) {
+	for (cur = trans; cur; cur = cur->next) {
 		if (cur == tc) {
 			spin_unlock(&translock);
-			return -EBUSY;
+			return res;
 		}
 	}
 
-	tc->owner = owner;
-	list_add(&tc->list, &trans);
+	tc->next = trans;
+	trans = tc;
 	printk("Registered codec translator '%s' with %d transcoders (srcs=%08x, dsts=%08x)\n", 
 	       tc->name, tc->numchannels, tc->srcfmts, tc->dstfmts);
+	res = 0;
 	spin_unlock(&translock);
 
-	return 0;
+	return res;
 }
 
 /* Unregister a transcoder */
 int zt_transcoder_unregister(struct zt_transcoder *tc) 
 {
-	struct zt_transcoder *cur, *next;
+	struct zt_transcoder *cur, *prev;
+	int res = -EINVAL;
 
 	spin_lock(&translock);
-	list_for_each_entry_safe(cur, next, &trans, list) {
-		if (cur == tc) {
-			list_del_init(&cur->list);
+	for (cur = trans, prev = NULL; cur; prev = cur, cur = cur->next) {
+		if (cur == tc)
 			break;
-		}
 	}
 
 	if (!cur) {
 		spin_unlock(&translock);
-		return -EINVAL;
+		return res;
 	}
 
+	if (prev)
+		prev->next = tc->next;
+	else
+		trans = tc->next;
+	tc->next = NULL;
 	printk("Unregistered codec translator '%s' with %d transcoders (srcs=%08x, dsts=%08x)\n", 
 	       tc->name, tc->numchannels, tc->srcfmts, tc->dstfmts);
+	res = 0;
 	spin_unlock(&translock);
 
-	return 0;
+	return res;
 }
 
 /* Alert a transcoder */
@@ -178,8 +185,7 @@ static int zt_tc_open(struct inode *inode, struct file *file)
 	
 	memset(ztc, 0, sizeof(*ztc));
 	memset(zth, 0, sizeof(*zth));
-	ztc->transient = 1;
-	ztc->busy = 1;
+	ztc->flags.transient = ztc->flags.busy = 1;
 	ztc->tch = zth;
 	if (debug)
 		printk("Allocated Transcoder Channel, header is at %p!\n", zth);
@@ -201,7 +207,7 @@ static void ztc_release(struct zt_transcoder_channel *ztc)
 	if (!ztc)
 		return;
 
-	ztc->busy = 0;
+	ztc->flags.busy = 0;
 
 	if (ztc->tch) {
 		for (page = virt_to_page(zth);
@@ -213,12 +219,12 @@ static void ztc_release(struct zt_transcoder_channel *ztc)
 
 	ztc->tch = NULL;
 
-	if (ztc->have_reference) {
+	if (ztc->flags.have_reference) {
 		module_put(ztc->parent->owner);
-		ztc->have_reference = 0;
+		ztc->flags.have_reference = 0;
 	}
 
-	if (ztc->transient);
+	if (ztc->flags.transient)
 		kfree(ztc);
 
 	if (debug)
@@ -244,7 +250,7 @@ static int do_allocate(struct zt_transcoder_channel **ztc)
 	    ((*ztc)->dstfmt != zth->dstfmt)) {
 		/* Find new transcoder */
 		spin_lock(&translock);
-		list_for_each_entry(tc, &trans, list) {
+		for (tc = trans; tc && !newztc; tc = tc->next) {
 			if (!(tc->srcfmts & zth->srcfmt))
 				continue;
 
@@ -253,10 +259,9 @@ static int do_allocate(struct zt_transcoder_channel **ztc)
 
 			match = 1;
 			for (x = 0; x < tc->numchannels; x++) {
-				if (tc->channels[x].busy)
+				if (tc->channels[x].flags.busy)
 					continue;
-
-				if (tc->channels[x].chan_built &&
+				if (tc->channels[x].flags.chan_built &&
 				    ((zth->srcfmt | zth->dstfmt) != tc->channels[x].built_fmts))
 					continue;
 
@@ -264,8 +269,7 @@ static int do_allocate(struct zt_transcoder_channel **ztc)
 					continue;
 
 				newztc = &tc->channels[x];
-				newztc->busy = 1;
-				newztc->have_reference = 1;
+				newztc->flags.busy = 1;
 				break;
 			}
 		}
@@ -279,7 +283,14 @@ static int do_allocate(struct zt_transcoder_channel **ztc)
 		(*ztc) = newztc;
 		(*ztc)->tch = origztc->tch;
 		origztc->tch = NULL;
-		(*ztc)->transient = 0;
+		/* ensure that the 'busy' flag doesn't get cleared,
+		   even for a short time, so no other thread will
+		   grab this channel
+		*/
+		origztc->flags.busy = 1;
+		(*ztc)->flags = origztc->flags;
+		(*ztc)->flags.transient = 0;
+		(*ztc)->flags.have_reference = 1;
 		ztc_release(origztc);
 	}
 
@@ -295,7 +306,7 @@ static int wait_busy(struct zt_transcoder_channel *ztc)
 	int ret;
 
 	for (;;) {
-		if (!(ztc->tch->busy))
+		if (!ztc->tch->busy)
 			return 0;
 		if ((ret = schluffen(&ztc->ready)))
 			return ret;
@@ -312,16 +323,10 @@ static int zt_tc_getinfo(unsigned long data)
 		return -EFAULT;
 
 	spin_lock(&translock);
-	x = info.tcnum;
-	list_for_each_entry(tc, &trans, list) {
-		if (!x)
-			break;
-		else
-			x--;
-	}
+	for (tc = trans, x = info.tcnum; tc && x; tc = tc->next, x--);
 	spin_unlock(&translock);
 
-	if (x || !tc)
+	if (!tc)
 		return -ENOSYS;
 
 	strncpy(info.name, tc->name, sizeof(info.name) - 1);
@@ -357,9 +362,9 @@ static int zt_tc_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 		break;
 	case ZT_TCOP_RELEASE:
 		ret = ztc->parent->operation(ztc, ZT_TCOP_RELEASE);
-		if (ztc->have_reference) {
+		if (ztc->flags.have_reference) {
 			module_put(ztc->parent->owner);
-			ztc->have_reference = 0;
+			ztc->flags.have_reference = 0;
 		}
 		break;
 	case ZT_TCOP_TRANSCODE: