control: use reference-counted pid

Instead of storing the PID number, take a reference to the task's pid
structure.  This protects against duplicates due to PID overflows, and
using pid_vnr() ensures that the PID returned by snd_ctl_elem_info() is
correct as seen from the current namespace.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 3 insertions, 1 deletions

diff --git a/include/sound/control.h b/include/sound/control.h
index 3517745d0a2d..112374dc0c58 100644
--- a/include/sound/control.h
+++ b/include/sound/control.h
@@ -86,10 +86,12 @@ struct snd_kctl_event {
 
 #define snd_kctl_event(n) list_entry(n, struct snd_kctl_event, list)
 
+struct pid;
+
 struct snd_ctl_file {
         struct list_head list;          /* list of all control files */
         struct snd_card *card;
-        pid_t pid;
+        struct pid *pid;
         int prefer_pcm_subdevice;
         int prefer_rawmidi_subdevice;
         wait_queue_head_t change_sleep;