ALSA: pcm: introduce INFO_NO_REWINDS flag

ALSA: pcm: introduce INFO_NO_REWINDS flag

When the hardware can only deal with a monotonically increasing
appl_ptr, this flag can be set.

In case the application requests a rewind, be it with a
snd_pcm_rewind() or with a direct change of a mmap'ed pointer followed
by a SNDRV_PCM_IOCTL_SYNC_PTR, this patch checks if a rewind
occurred and returns an error.

Credits to Takashi Iwai for identifying the path with SYNC_PTR and
suggesting the pointer checks.

Suggested-by: Takashi Iwai <[email protected]>
Reviewed-by: Takashi Iwai <[email protected]>
Reviewed-by: Ranjani Sridharan <[email protected]>
Reviewed-by: Kai Vehmanen <[email protected]>
Signed-off-by: Pierre-Louis Bossart <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Mark Brown <[email protected]>