linux.git/sound/core/timer.c, branch v5.8

ALSA: timer: fix nsec/sec initialization confusion

2020-01-12T08:08:22+00:00

GCC reports a warning with W=1:

sound/core/timer.c: In function ‘snd_timer_user_read’:
sound/core/timer.c:2219:19: warning: initialized field overwritten
[-Woverride-init]
 2219 |     .tstamp_sec = tread->tstamp_nsec,
      |                   ^~~~~
sound/core/timer.c:2219:19: note: (near initialization for
‘(anonymous).tstamp_sec’)

Assigning nsec values to sec fields is problematic in general, even
more so when the initial goal was to survive the 2030 timer
armageddon.

Fix by using the proper field in the initialization

Cc: Baolin Wang 
Cc: Arnd Bergmann 
Fixes: 07094ae6f9527 ("ALSA: Avoid using timespec for struct snd_timer_tread")
Signed-off-by: Pierre-Louis Bossart 
Acked-by: Arnd Bergmann 
Link: https://lore.kernel.org/r/20200111203325.20498-1-pierre-louis.bossart@linux.intel.com
Signed-off-by: Takashi Iwai

ALSA: timer: Constify snd_timer_hardware definitions

2020-01-03T08:24:07+00:00

Most of snd_timer_hardware definitions do simply copying to another
struct as-is.  Mark them as const for further optimization.

There should be no functional changes by this patch.

Link: https://lore.kernel.org/r/20200103081714.9560-21-tiwai@suse.de
Signed-off-by: Takashi Iwai

ALSA: core: Constify snd_device_ops definitions

2020-01-03T08:23:51+00:00

Now we may declare const for snd_device_ops definitions, so let's do
it for optimization.

There should be no functional changes by this patch.

Link: https://lore.kernel.org/r/20200103081714.9560-5-tiwai@suse.de
Signed-off-by: Takashi Iwai

ALSA: Avoid using timespec for struct snd_timer_tread

2019-12-13T10:25:57+00:00

The struct snd_timer_tread will use 'timespec' type variables to record
timestamp, which is not year 2038 safe on 32bits system.

Since the struct snd_timer_tread is passed through read() rather than
ioctl(), and the read syscall has no command number that lets us pick
between the 32-bit or 64-bit version of this structure.

Thus we introduced one new command SNDRV_TIMER_IOCTL_TREAD64 and new
struct snd_timer_tread64 replacing timespec with s64 type to handle
64bit time_t. That means we will set tu->tread = TREAD_FORMAT_64BIT
when user space has a 64bit time_t, then we will copy to user with
struct snd_timer_tread64. Otherwise we will use 32bit time_t variables
when copying to user.

Moreover this patch replaces timespec type with timespec64 type and
related y2038 safe APIs.

Signed-off-by: Baolin Wang 
Signed-off-by: Arnd Bergmann

ALSA: Avoid using timespec for struct snd_timer_status

2019-12-11T21:06:15+00:00

struct snd_timer_status uses 'timespec' type variables to record
timestamp, which will be changed to an incompatible layout with
updated user space using 64-bit time_t.

To handle both the old and the new layout on 32-bit architectures,
this patch introduces 'struct snd_timer_status32' and 'struct snd_timer_status64'
to handle 32bit time_t and 64bit time_t in native mode and compat mode,
which replaces timespec with s64 type.

When glibc changes time_t to 64-bit, any recompiled program will issue
ioctl commands that the kernel does not understand without this patch.

In the public uapi header, snd_timer_status is now guarded by
an #ifndef __KERNEL__ to avoid referencing 'struct timespec'.
The timespec definition will be removed from the kernel to prevent
new y2038 bugs and to avoid the conflict with an incompatible libc
type of the same name.

Signed-off-by: Baolin Wang 
Signed-off-by: Arnd Bergmann

ALSA: Replace timespec with timespec64

2019-12-11T21:06:14+00:00

Since timespec is not year 2038 safe on 32bit system, and we need to
convert all timespec variables to timespec64 type for sound subsystem.

This patch is used to do preparation for following patches, that will
convert all structures defined in uapi/sound/asound.h to use 64-bit
time_t.

Signed-off-by: Baolin Wang 
Signed-off-by: Arnd Bergmann

ALSA: timer: Fix the breakage of slave link open

2019-11-11T17:37:06+00:00

A silly mistake was made while applying the fix for potential races in
commit 6a34367e52ca ("ALSA: timer: Fix possible race at assigning a
timer instance"): when a slave PCM is opened and succeeds, it doesn't
return but proceeds to the master timer open code instead.  Plug the
hole and beautify a bit.

Fixes: 6a34367e52ca ("ALSA: timer: Fix possible race at assigning a timer instance")
Reported-by: syzbot+4476917c053f60112c99@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/20191111173642.6093-1-tiwai@suse.de
Signed-off-by: Takashi Iwai

ALSA: timer: Fix possible race at assigning a timer instance

2019-11-08T13:52:44+00:00

When a new timer instance is created and assigned to the active link
in snd_timer_open(), the caller still doesn't (can't) set its callback
and callback data.  In both the user-timer and the sequencer-timer
code, they do manually set up the callbacks after calling
snd_timer_open().  This has a potential risk of race when the timer
instance is added to the already running timer target, as the callback
might get triggered during setting up the callback itself.

This patch tries to address it by changing the API usage slightly:

- An empty timer instance is created at first via the new function
  snd_timer_instance_new().  This object isn't linked to the timer
  list yet.
- The caller sets up the callbacks and others stuff for the new timer
  instance.
- The caller invokes snd_timer_open() with this instance, so that it's
  linked to the target timer.

For closing, do similarly:

- Call snd_timer_close().  This unlinks the timer instance from the
  timer list.
- Free the timer instance via snd_timer_instance_free() after that.

Signed-off-by: Takashi Iwai 
Link: https://lore.kernel.org/r/20191107192008.32331-4-tiwai@suse.de
Signed-off-by: Takashi Iwai

ALSA: timer: Make snd_timer_close() returning void

2019-11-08T13:52:43+00:00

The function doesn't return any useful value, so let's make it void to
be clearer.

Signed-off-by: Takashi Iwai 
Link: https://lore.kernel.org/r/20191107192008.32331-3-tiwai@suse.de
Signed-off-by: Takashi Iwai

ALSA: timer: Unify master/slave linking code

2019-11-08T13:52:42+00:00

The code in both snd_timer_check_master() and snd_timer_check_slave()
are almost identical, both check whether the master/slave link and
does linkage.  Factor out the common code and call it from both
functions for readability.

Signed-off-by: Takashi Iwai 
Link: https://lore.kernel.org/r/20191107192008.32331-2-tiwai@suse.de
Signed-off-by: Takashi Iwai