[PATCH]: Keep sound-module usage correct, even if audio_open fails

[Chris Rankin]

Hi,
I noticed that if you try to (e.g.) play two WAV file simultaneously,
then not only does the second one fail ("Device or resource busy", of
course) but the sound-card module's usage count breaks.

Here is a patch. And Alan, since you seem to be the person collecting
these sound patches, I should point out that this patch to
drivers/sound/audio.c completely replaces the patch to audio.c that I
submitted earlier. That patch was related to the coprocessor module
locking, but this new patch has reworked the way that audio_open()
cleans up after itself anyway. This clean-up now includes the
coprocessor too.

Cheers,
Chris

--- linux-vanilla/drivers/sound/audio.c Fri Aug 11 16:26:43 2000
+++ linux-2.4.0-ac3/drivers/sound/audio.c       Wed Jan 10 23:53:23 2001
@@ -21,6 +21,9 @@
  * Daniel Rodriksson: reworked the use of the device specific copy_user
  *                    still generic
  * Horst von Brand:  Add missing #include <linux/string.h>
+ * Chris Rankin    : Update the module-usage counter for the coprocessor,
+ *                   and decrement the counters again if we cannot open
+ *                   the audio device.
  */
 
 #include <linux/stddef.h>
@@ -71,6 +74,8 @@
        int bits;
        int dev_type = dev & 0x0f;
        int mode = translate_mode(file);
+       const struct audio_driver *driver;
+       const struct coproc_operations *coprocessor;
 
        dev = dev >> 4;
 
@@ -82,18 +87,20 @@
        if (dev < 0 || dev >= num_audiodevs)
                return -ENXIO;
 
-       if (audio_devs[dev]->d->owner)
-               __MOD_INC_USE_COUNT (audio_devs[dev]->d->owner);
+       driver = audio_devs[dev]->d;
+       if (driver->owner)
+               __MOD_INC_USE_COUNT(driver->owner);
 
        if ((ret = DMAbuf_open(dev, mode)) < 0)
-               return ret;
+               goto error_1;
 
-       if (audio_devs[dev]->coproc) {
-               if ((ret = audio_devs[dev]->coproc->
-                       open(audio_devs[dev]->coproc->devc, COPR_PCM)) < 0) {
-                       audio_release(dev, file);
+       if ( (coprocessor = audio_devs[dev]->coproc) != NULL ) {
+               if (coprocessor->owner)
+                       __MOD_INC_USE_COUNT(coprocessor->owner);
+
+               if ((ret = coprocessor->open(coprocessor->devc, COPR_PCM)) < 0) {
                        printk(KERN_WARNING "Sound: Can't access coprocessor 
device\n");
-                       return ret;
+                       goto error_2;
                }
        }
        
@@ -106,6 +113,20 @@
 
        audio_devs[dev]->audio_mode = AM_NONE;
 
+       return 0;
+
+       /*
+        * Clean-up stack: this is what needs (un)doing if
+        * we can't open the audio device ...
+        */
+       error_2:
+       if (coprocessor->owner)
+               __MOD_DEC_USE_COUNT(coprocessor->owner);
+       DMAbuf_release(dev, mode);
+
+       error_1:
+       if (driver->owner)
+               __MOD_DEC_USE_COUNT(driver->owner);
 
        return ret;
 }
@@ -156,7 +177,8 @@
 
 void audio_release(int dev, struct file *file)
 {
-       int             mode = translate_mode(file);
+       const struct coproc_operations *coprocessor;
+       int mode = translate_mode(file);
 
        dev = dev >> 4;
 
@@ -176,8 +198,12 @@
        if (mode & OPEN_WRITE)
                sync_output(dev);
 
-       if (audio_devs[dev]->coproc)
-               audio_devs[dev]->coproc->close(audio_devs[dev]->coproc->devc, 
COPR_PCM);
+       if ( (coprocessor = audio_devs[dev]->coproc) != NULL ) {
+               coprocessor->close(coprocessor->devc, COPR_PCM);
+
+               if (coprocessor->owner)
+                       __MOD_DEC_USE_COUNT(coprocessor->owner);
+       }
        DMAbuf_release(dev, mode);
 
        if (audio_devs[dev]->d->owner)
-
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