git: bf3a355a874a - stable/14 - sound: Remove redundant refcount checks in vchan_setnew()

The branch stable/14 has been updated by christos:

URL: https://cgit.FreeBSD.org/src/commit/?id=bf3a355a874abfcf7ab77bff84bc355ef79ef0a6

commit bf3a355a874abfcf7ab77bff84bc355ef79ef0a6
Author:     Christos Margiolis <christos@FreeBSD.org>
AuthorDate: 2024-10-25 11:36:51 +0000
Commit:     Christos Margiolis <christos@FreeBSD.org>
CommitDate: 2024-10-27 16:32:30 +0000

    sound: Remove redundant refcount checks in vchan_setnew()
    
    When adding a new vchan, we are looking for a parent channel which
    either already has vchans (i.e CHN_F_HAS_VCHAN), or does not, but is
    also not being used (i.e !CHN_F_BUSY). Since CHN_F_BUSY essentially
    tells us if the channel is currently being used or not, there is no need
    to check if the channel's refcount is 0 as well.
    
    When removing a vchan, we first check if we have only 1 vchan allocated
    that is also being used (so we cannot remove it at the moment), and then
    we check if the vchan is not busy and remove it. Again, checking
    CHN_F_BUSY is enough.
    
    Sponsored by:   The FreeBSD Foundation
    MFC after:      2 days
    Reviewed by:    dev_submerge.ch
    Differential Revision:  https://reviews.freebsd.org/D47268
    
    (cherry picked from commit 43c0b593c2c3b2c07009c031a0e7e8190a45b31a)
---
 sys/dev/sound/pcm/vchan.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/sys/dev/sound/pcm/vchan.c b/sys/dev/sound/pcm/vchan.c
index c9db9d79847b..ed13a3c55961 100644
--- a/sys/dev/sound/pcm/vchan.c
+++ b/sys/dev/sound/pcm/vchan.c
@@ -928,7 +928,6 @@ vchan_setnew(struct snddev_info *d, int direction, int newcnt)
 			CHN_LOCK(c);
 			if (c->direction == direction &&
 			    ((c->flags & CHN_F_HAS_VCHAN) || (vcnt == 0 &&
-			    c->refcount < 1 &&
 			    !(c->flags & (CHN_F_BUSY | CHN_F_VIRTUAL))))) {
 				/*
 				 * Reuse hw channel with vchans already
@@ -987,12 +986,11 @@ vchan_setnew(struct snddev_info *d, int direction, int newcnt)
 			}
 			CHN_FOREACH_SAFE(ch, c, nch, children) {
 				CHN_LOCK(ch);
-				if (vcnt == 1 && c->refcount > 0) {
+				if (vcnt == 1 && ch->flags & CHN_F_BUSY) {
 					CHN_UNLOCK(ch);
 					break;
 				}
-				if (!(ch->flags & CHN_F_BUSY) &&
-				    ch->refcount < 1) {
+				if (!(ch->flags & CHN_F_BUSY)) {
 					err = vchan_destroy(ch);
 					if (err == 0)
 						vcnt--;