pcm: fix 64-bit SNDRV_PCM_IOCTL_STATUS ABI breakage

Commit cf40ea169aad (pcm: support for audio timestamps) added the new
audio_tstamp field to struct sndrv_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>

diff --git a/include/sound/asound.h b/include/sound/asound.h
index 16d03e8..8fdad91 100644 (file)
--- a/include/sound/asound.h
+++ b/include/sound/asound.h
@@ -427,8 +427,9 @@ struct sndrv_pcm_status {
        sndrv_pcm_uframes_t avail_max;  /* max frames available on hw since last status */
        sndrv_pcm_uframes_t overrange;  /* count of ADC (capture) overrange detections from last status */
        int suspended_state;            /* suspended stream state */
+       u_int32_t 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 sndrv_pcm_mmap_status {