ALSA: core: fix 64-bit SNDRV_PCM_IOCTL_STATUS ABI breakage

Commit 4eeaaeaea (ALSA: core: add hooks for audio timestamps) added the
new audio_tstamp field to struct snd_pcm_status.  However, struct
timespec requires 64-bit alignment, so the 64-bit compiler would insert
32 bits of padding before this field, which broke SNDRV_PCM_IOCTL_STATUS
with error messages like this:

  kernel: unknown ioctl = 0x80984120

To solve this, insert the padding explicitly so that it can be taken
into account when calculating the ABI structure size.

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

2 files changed, 4 insertions, 2 deletions

diff --git a/include/uapi/sound/asound.h b/include/uapi/sound/asound.h
index 85b2e4dde883..515b8fcd1ca9 100644
--- a/include/uapi/sound/asound.h
+++ b/include/uapi/sound/asound.h
@@ -407,8 +407,9 @@ struct snd_pcm_status {
         snd_pcm_uframes_t avail_max;    /* max frames available on hw since last status */
         snd_pcm_uframes_t overrange;    /* count of ADC (capture) overrange detections from last status */
         snd_pcm_state_t suspended_state; /* suspended stream state */
+        __u32 reserved_alignment;       /* must be filled with zero */
         struct timespec audio_tstamp;   /* from sample counter or wall clock */
-        unsigned char reserved[60-sizeof(struct timespec)]; /* must be filled with zero */
+        unsigned char reserved[56-sizeof(struct timespec)]; /* must be filled with zero */
 };
 
 struct snd_pcm_mmap_status {
diff --git a/sound/core/pcm_compat.c b/sound/core/pcm_compat.c
index af2a3fdb8828..af49721ba0e3 100644
--- a/sound/core/pcm_compat.c
+++ b/sound/core/pcm_compat.c
@@ -190,8 +190,9 @@ struct snd_pcm_status32 {
         u32 avail_max;
         u32 overrange;
         s32 suspended_state;
+        u32 reserved_alignment;
         struct compat_timespec audio_tstamp;
-        unsigned char reserved[60-sizeof(struct compat_timespec)];
+        unsigned char reserved[56-sizeof(struct compat_timespec)];
 } __attribute__((packed));