[ALSA] Don't reject O_RDWR at opening PCM OSS with read/write-only device

Accept O_RDWR at opening a PCM OSS device that is read- or write-only,
just for the compatibility with the behavior of older versions.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>

1 files changed, 2 insertions, 0 deletions

diff --git a/sound/core/oss/pcm_oss.c b/sound/core/oss/pcm_oss.c
index f5ff4f4a16ee..472fce0ee0e8 100644
--- a/sound/core/oss/pcm_oss.c
+++ b/sound/core/oss/pcm_oss.c
@@ -2228,6 +2228,8 @@ static int snd_pcm_oss_open_file(struct file *file,
         for (idx = 0; idx < 2; idx++) {
                 if (setup[idx].disable)
                         continue;
+                if (! pcm->streams[idx].substream_count)
+                        continue; /* no matching substream */
                 if (idx == SNDRV_PCM_STREAM_PLAYBACK) {
                         if (! (f_mode & FMODE_WRITE))
                                 continue;