On Fri, 15 May 2020 18:24:08 +0200,
Maarten Baert wrote:
>
> The available size calculation did not handle wraparound correctly. Also, the
> underrun handling code confused slave_buffer_size with slave_boundary, causing
> another integer overflow that results in too many samples being skipped.
>
> Signed-off-by: Maarten Baert <maarten-baert@xxxxxxxxxxx>
Thanks, the code change looks correct but the embedded patch isn't
applicable. Indeed the patch seems somehow malformed.
Could you repost the proper one, at best with git-send-email?
thanks,
Takashi
> ---
> src/pcm/pcm_dmix.c | 16 +++++++++-------
> 1 file changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/src/pcm/pcm_dmix.c b/src/pcm/pcm_dmix.c
> index 843fa316..b5fdb240 100644
> --- a/src/pcm/pcm_dmix.c
> +++ b/src/pcm/pcm_dmix.c
> @@ -315,11 +315,12 @@ static void snd_pcm_dmix_sync_area(snd_pcm_t *pcm)
> /* check the available size in the local buffer
> * last_appl_ptr keeps the last updated position
> */
> - size = dmix->appl_ptr - dmix->last_appl_ptr;
> + if (dmix->appl_ptr >= dmix->last_appl_ptr)
> + size = dmix->appl_ptr - dmix->last_appl_ptr;
> + else
> + size = dmix->appl_ptr + (pcm->boundary - dmix->last_appl_ptr);
> if (! size)
> return;
> - if (size >= pcm->boundary / 2)
> - size = pcm->boundary - size;
> /* the slave_app_ptr can be far behind the slave_hw_ptr */
> /* reduce mixing and errors here - just skip not catched writes */
> @@ -328,18 +329,19 @@ static void snd_pcm_dmix_sync_area(snd_pcm_t *pcm)
> else
> slave_size = dmix->slave_appl_ptr + (dmix->slave_boundary - dmix->slave_hw_ptr);
> if (slave_size > dmix->slave_buffer_size) {
> - transfer = dmix->slave_buffer_size - slave_size;
> + transfer = dmix->slave_boundary - slave_size;
> if (transfer > size)
> transfer = size;
> dmix->last_appl_ptr += transfer;
> dmix->last_appl_ptr %= pcm->boundary;
> dmix->slave_appl_ptr += transfer;
> dmix->slave_appl_ptr %= dmix->slave_boundary;
> - size = dmix->appl_ptr - dmix->last_appl_ptr;
> + if (dmix->appl_ptr >= dmix->last_appl_ptr)
> + size = dmix->appl_ptr - dmix->last_appl_ptr;
> + else
> + size = dmix->appl_ptr + (pcm->boundary - dmix->last_appl_ptr);
> if (! size)
> return;
> - if (size >= pcm->boundary / 2)
> - size = pcm->boundary - size;
> }
> /* check the available size in the slave PCM buffer */
> --
> 2.26.2
>
