[ALSA] dynamic minors (3/6): store device-specific object pointers dynamically

Instead of storing the pointers to the device-specific structures in an
array, put them into the struct snd_minor, and look them up dynamically.

This makes the device type modules independent of the minor number
encoding.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>

1 files changed, 24 insertions, 3 deletions

diff --git a/sound/core/sound_oss.c b/sound/core/sound_oss.c
index afbfd8df129..b9e89cac4c5 100644
--- a/sound/core/sound_oss.c
+++ b/sound/core/sound_oss.c
@@ -38,9 +38,25 @@
 #define SNDRV_OSS_MINORS 128
 
 static struct snd_minor *snd_oss_minors[SNDRV_OSS_MINORS];
-
 static DECLARE_MUTEX(sound_oss_mutex);
 
+void *snd_lookup_oss_minor_data(unsigned int minor, int type)
+{
+        struct snd_minor *mreg;
+        void *private_data;
+
+        if (minor > ARRAY_SIZE(snd_oss_minors))
+                return NULL;
+        down(&sound_oss_mutex);
+        mreg = snd_oss_minors[minor];
+        if (mreg && mreg->type == type)
+                private_data = mreg->private_data;
+        else
+                private_data = NULL;
+        up(&sound_oss_mutex);
+        return private_data;
+}
+
 static int snd_oss_kernel_minor(int type, struct snd_card *card, int dev)
 {
         int minor;
@@ -78,7 +94,8 @@ static int snd_oss_kernel_minor(int type, struct snd_card *card, int dev)
 }
 
 int snd_register_oss_device(int type, struct snd_card *card, int dev,
-                            struct file_operations *f_ops, const char *name)
+                            struct file_operations *f_ops, void *private_data,
+                            const char *name)
 {
         int minor = snd_oss_kernel_minor(type, card, dev);
         int minor_unit;
@@ -97,6 +114,7 @@ int snd_register_oss_device(int type, struct snd_card *card, int dev,
         preg->card = card ? card->number : -1;
         preg->device = dev;
         preg->f_ops = f_ops;
+        preg->private_data = private_data;
         down(&sound_oss_mutex);
         snd_oss_minors[minor] = preg;
         minor_unit = SNDRV_MINOR_OSS_DEVICE(minor);
@@ -121,6 +139,7 @@ int snd_register_oss_device(int type, struct snd_card *card, int dev,
                                                           carddev);
                 if (register2 != track2)
                         goto __end;
+                snd_oss_minors[track2] = preg;
         }
         up(&sound_oss_mutex);
         return 0;
@@ -163,8 +182,10 @@ int snd_unregister_oss_device(int type, struct snd_card *card, int dev)
                 track2 = SNDRV_MINOR_OSS(cidx, SNDRV_MINOR_OSS_DMMIDI1);
                 break;
         }
-        if (track2 >= 0)
+        if (track2 >= 0) {
                 unregister_sound_special(track2);
+                snd_oss_minors[track2] = NULL;
+        }
         snd_oss_minors[minor] = NULL;
         up(&sound_oss_mutex);
         kfree(mptr);