Apply reference counting patch. Fixes problem of two applications

opening the device, eg one read only and one write only, and the
reference count being non-zero when both exit rendering device
permanently busy.

PR:		kern/35004
Submitted by:	Bill Wells
MFC after:	3 days

1 files changed, 33 insertions, 35 deletions

diff --git a/sys/dev/sound/pcm/dsp.c b/sys/dev/sound/pcm/dsp.c
index b7eb4b9..1d4a660 100644
--- a/sys/dev/sound/pcm/dsp.c
+++ b/sys/dev/sound/pcm/dsp.c
@@ -283,40 +283,34 @@ dsp_open(dev_t i_dev, int flags, int mode, struct thread *td)
 	/* finished with snddev, new channels still locked */
 
 	/* bump refcounts, reset and unlock any channels that we just opened */
-	if (rdch) {
-		if (flags & FREAD) {
-	        	if (chn_reset(rdch, fmt)) {
-				pcm_lock(d);
-				pcm_chnrelease(rdch);
-				if (wrch && (flags & FWRITE))
-					pcm_chnrelease(wrch);
-				pcm_unlock(d);
-				splx(s);
-				return ENODEV;
-			}
-			if (flags & O_NONBLOCK)
-				rdch->flags |= CHN_F_NBIO;
-		} else
-			CHN_LOCK(rdch);
+	if (flags & FREAD) {
+		if (chn_reset(rdch, fmt)) {
+			pcm_lock(d);
+			pcm_chnrelease(rdch);
+			if (wrch && (flags & FWRITE))
+				pcm_chnrelease(wrch);
+			pcm_unlock(d);
+			splx(s);
+			return ENODEV;
+		}
+		if (flags & O_NONBLOCK)
+			rdch->flags |= CHN_F_NBIO;
 
 		pcm_chnref(rdch, 1);
 	 	CHN_UNLOCK(rdch);
 	}
-	if (wrch) {
-		if (flags & FWRITE) {
-	        	if (chn_reset(wrch, fmt)) {
-				pcm_lock(d);
-				pcm_chnrelease(wrch);
-				if (rdch && (flags & FREAD))
-					pcm_chnrelease(rdch);
-				pcm_unlock(d);
-				splx(s);
-				return ENODEV;
-			}
-			if (flags & O_NONBLOCK)
-				wrch->flags |= CHN_F_NBIO;
-		} else
-			CHN_LOCK(wrch);
+	if (flags & FWRITE) {
+		if (chn_reset(wrch, fmt)) {
+			pcm_lock(d);
+			pcm_chnrelease(wrch);
+			if (rdch && (flags & FREAD))
+				pcm_chnrelease(rdch);
+			pcm_unlock(d);
+			splx(s);
+			return ENODEV;
+		}
+		if (flags & O_NONBLOCK)
+			wrch->flags |= CHN_F_NBIO;
 
 		pcm_chnref(wrch, 1);
 	 	CHN_UNLOCK(wrch);
@@ -345,18 +339,23 @@ dsp_close(dev_t i_dev, int flags, int mode, struct thread *td)
 	if (rdch) {
 		CHN_LOCK(rdch);
 		if (pcm_chnref(rdch, -1) > 0) {
-			CHN_UNLOCK(rdch);
 			exit = 1;
 		}
+		CHN_UNLOCK(rdch);
 	}
 	if (wrch) {
 		CHN_LOCK(wrch);
 		if (pcm_chnref(wrch, -1) > 0) {
-			CHN_UNLOCK(wrch);
 			exit = 1;
 		}
+		CHN_UNLOCK(wrch);
 	}
+	/* XXX And what happens if one of the channels had 2 references and
+	the other has but one? The latter won't get reset. Can that
+	happen? */
 	if (exit) {
+		i_dev->si_drv1 = NULL;
+		i_dev->si_drv2 = NULL;
 		pcm_unlock(d);
 		splx(s);
 		return 0;
@@ -367,9 +366,6 @@ dsp_close(dev_t i_dev, int flags, int mode, struct thread *td)
 	if (pcm_getfakechan(d))
 		pcm_getfakechan(d)->flags = 0;
 
-	i_dev->si_drv1 = NULL;
-	i_dev->si_drv2 = NULL;
-
 	dsp_set_flags(i_dev, dsp_get_flags(i_dev) & ~SD_F_TRANSIENT);
 	pcm_unlock(d);
 
@@ -385,6 +381,8 @@ dsp_close(dev_t i_dev, int flags, int mode, struct thread *td)
 		chn_reset(wrch, 0);
 		pcm_chnrelease(wrch);
 	}
+	i_dev->si_drv1 = NULL;
+	i_dev->si_drv2 = NULL;
 
 	splx(s);
 	return 0;