[alsa-devel] [PATCH v6 0/8] Fix year 2038 issue for sound subsystem

[Arnd Bergmann]

On Wed, Nov 13, 2019 at 6:04 PM Takashi Iwai <tiwai at suse.de> wrote:
>
> On Wed, 13 Nov 2019 17:51:57 +0100,
> Arnd Bergmann wrote:
> >
> > On Wed, Nov 13, 2019 at 5:40 PM Takashi Iwai <tiwai at suse.de> wrote:
> > > On Wed, 13 Nov 2019 15:32:44 +0100, Arnd Bergmann wrote:
> >
> > > > We had discussed alternatives for this one last time, and decided
> > > > to go with the solution I posted here. The main alternative would
> > > > be to change the 'timespec' in snd_timer_tread to a fixed-length
> > > > structure based on two 'long' members. This would avoid the
> > > > need to match the command with the time_t type, but the cost would
> > > > be requiring CLOCK_MONOTONIC timestamps to avoid the
> > > > overflow, and changing all application source code that requires
> > > > the type to be compatible with 'timespec'.
> > >
> > > Fair enough.
> > >
> > > One thing I forgot to mention: when we add/modify the ioctl or ABI, we
> > > need to increment the protocol version, e.g. SNDRV_PCM_VERSION to
> > > indicate user-space the supported ABI.  Please change these in your
> > > next patches, too.
> >
> > Just to confirm: this should be a simple one-line patch at the end of the
> > series like
> >
> > diff --git a/tools/include/uapi/sound/asound.h
> > b/tools/include/uapi/sound/asound.h
> > index df1153cea0b7..72e8380c6dcd 100644
> > --- a/include/uapi/sound/asound.h
> > +++ b/include/uapi/sound/asound.h
> > @@ -154,7 +154,7 @@ struct snd_hwdep_dsp_image {
> >   *                                                                           *
> >   *****************************************************************************/
> >
> > -#define SNDRV_PCM_VERSION              SNDRV_PROTOCOL_VERSION(2, 0, 14)
> > +#define SNDRV_PCM_VERSION              SNDRV_PROTOCOL_VERSION(2, 0, 15)
> >
> >  typedef unsigned long snd_pcm_uframes_t;
> >  typedef signed long snd_pcm_sframes_t;
> >
> > right? Most other kernel interfaces have no version numbering, so
> > I don't know what policy you have here.
>
> I don't mind much about that, so it's up to you -- we can fold this
> change into the patch that actually adds or modifies the ioctl, too.

I've added the patch below to the end of the series now, will repost
the series  after no more comments come in for this version.
Having a single patch to update the version seems better than updating
it multiple times with each patch touching the ABI in this series.

      Arnd

commit b83a3eaece9b445f897a6f5ac2a903f2566a0e9d
Author: Arnd Bergmann <arnd at arndb.de>
Date:   Wed Nov 13 17:49:14 2019 +0100

    ALSA: bump uapi version number

    Change SNDRV_PCM_VERSION to indicate the addition of the time64
    version of the mmap interface and these ioctl commands:

    SNDRV_PCM_IOCTL_SYNC
    SNDRV_RAWMIDI_IOCTL_STATUS
    SNDRV_PCM_IOCTL_STATUS
    SNDRV_PCM_IOCTL_STATUS_EXT
    SNDRV_TIMER_IOCTL_TREAD
    SNDRV_TIMER_IOCTL_STATUS

    32-bit applications built with 64-bit time_t require both the headers
    and the running kernel to support at least API version 2.0.15. When
    built with earlier kernel headers, some of these may not work
    correctly, so applications are encouraged to fail compilation like

     #if SNDRV_PCM_VERSION < SNDRV_PROTOCOL_VERSION(2, 0, 15)
     extern int __fail_build_for_time_64[sizeof(long) - sizeof(time_t)];
     #endif

    or provide their own updated copy of the header file.

    Signed-off-by: Arnd Bergmann <arnd at arndb.de>

diff --git a/include/uapi/sound/asound.h b/include/uapi/sound/asound.h
index 25dbf71fa667..5cddfe62c97a 100644
--- a/include/uapi/sound/asound.h
+++ b/include/uapi/sound/asound.h
@@ -156,7 +156,7 @@ struct snd_hwdep_dsp_image {
  *                                                                           *
  *****************************************************************************/

-#define SNDRV_PCM_VERSION              SNDRV_PROTOCOL_VERSION(2, 0, 14)
+#define SNDRV_PCM_VERSION              SNDRV_PROTOCOL_VERSION(2, 0, 15)

 typedef unsigned long snd_pcm_uframes_t;
 typedef signed long snd_pcm_sframes_t;