linux.git/sound/core/seq/seq_timer.c, branch v4.19.39

ALSA: seq: Avoid open-code for getting timer resolution

2018-05-18T06:49:13+00:00

Instead of open-coding for getting the timer resolution, use the
standard snd_timer_resolution() helper.

The original code falls back to the callback function when the
resolution is zero, but it must be always so when the callback
function is defined.  So this should be no functional change.

Signed-off-by: Takashi Iwai

ALSA: seq: Process queue tempo/ppq change in a shot

2018-01-15T15:48:36+00:00

The SNDRV_SEQ_IOCTL_SET_QUEUE_TEMPO ioctl sets the tempo and the ppq
in a single call, while the current implementation updates each value
one by one.  This is a bit racy, and also suboptimal from the
performance POV, as each call does re-acquire the lock and invokes
the update of ALSA timer resolution.

This patch reorganizes the code slightly so that we change both the
tempo and the ppq in a shot.  The skew value can be put into the same
lock, but this is rather a rarely used feature and completely
independent from the temp/ppq (it's evaluated only in the interrupt),
so it's left as it was.

Signed-off-by: Takashi Iwai

ALSA: seq: Remove spurious WARN_ON() at timer check

2017-11-30T09:08:28+00:00

The use of snd_BUG_ON() in ALSA sequencer timer may lead to a spurious
WARN_ON() when a slave timer is deployed as its backend and a
corresponding master timer stops meanwhile.  The symptom was triggered
by syzkaller spontaneously.

Since the NULL timer is valid there, rip off snd_BUG_ON().

Reported-by: syzbot 
Cc: 
Signed-off-by: Takashi Iwai

ALSA: seq: Fix time account regression

2016-10-25T14:00:46+00:00

The recent rewrite of the sequencer time accounting using timespec64
in the commit [3915bf294652: ALSA: seq_timer: use monotonic times
internally] introduced a bad regression.  Namely, the time reported
back doesn't increase but goes back and forth.

The culprit was obvious: the delta is stored to the result (cur_time =
delta), instead of adding the delta (cur_time += delta)!

Let's fix it.

Fixes: 3915bf294652 ('ALSA: seq_timer: use monotonic times internally')
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=177571
Reported-by: Yves Guillemot 
Cc:  # v4.8+
Signed-off-by: Takashi Iwai

ALSA: seq_timer: use monotonic times internally

2016-06-17T20:56:13+00:00

The sequencer client manager reports timestamps in units of unsigned
32-bit seconds/nanoseconds, but that does not suffer from the y2038
overflow because it stores only the delta since the 'last_update'
time was recorded.

However, the use of the do_gettimeofday() function is problematic
and we have to replace it to avoid the overflow on on 32-bit
architectures.

This uses 'struct timespec64' to record 'last_update', and changes
the code to use monotonic timestamps that do not suffer from leap
seconds and settimeofday updates.

As a side-effect, the code can now use the timespec64_sub() helper
and become more readable and also avoid a multiplication to convert
from microseconds to nanoseconds.

Signed-off-by: Arnd Bergmann 
Signed-off-by: Takashi Iwai

ALSA: seq: Fix yet another races among ALSA timer accesses

2016-02-01T11:23:29+00:00

ALSA sequencer may open/close and control ALSA timer instance
dynamically either via sequencer events or direct ioctls.  These are
done mostly asynchronously, and it may call still some timer action
like snd_timer_start() while another is calling snd_timer_close().
Since the instance gets removed by snd_timer_close(), it may lead to
a use-after-free.

This patch tries to address such a race by protecting each
snd_timer_*() call via the existing spinlock and also by avoiding the
access to timer during close call.

BugLink: http://lkml.kernel.org/r/CACT4Y+Z6RzW5MBr-HUdV-8zwg71WQfKTdPpYGvOeS7v4cyurNQ@mail.gmail.com
Reported-by: Dmitry Vyukov 
Cc: 
Signed-off-by: Takashi Iwai

ALSA: replace CONFIG_PROC_FS with CONFIG_SND_PROC_FS

2015-05-27T19:25:19+00:00

We may disable proc fs only for sound part, to reduce ALSA
memory footprint. So add CONFIG_SND_PROC_FS and replace the
old CONFIG_PROC_FSs in alsa code.

With sound proc fs disabled, we can save about 9KB memory
size on X86_64 platform.

Signed-off-by: Jie Yang 
Reviewed-by: Mark Brown 
Signed-off-by: Takashi Iwai

ALSA: seq: Drop superfluous error/debug messages after malloc failures

2015-03-10T14:41:18+00:00

The kernel memory allocators already report the errors when the
requested allocation fails, thus we don't need to warn it again in
each caller side.

Signed-off-by: Takashi Iwai

ALSA: seq: Use standard printk helpers

2014-02-14T07:14:18+00:00

Use the standard pr_xxx() helpers instead of home-baked snd_print*().

Signed-off-by: Takashi Iwai

ALSA: seq: Fix missing error handling in snd_seq_timer_open()

2013-03-11T08:40:36+00:00

snd_seq_timer_open() didn't catch the whole error path but let through
if the timer id is a slave.  This may lead to Oops by accessing the
uninitialized pointer.

 BUG: unable to handle kernel NULL pointer dereference at 00000000000002ae
 IP: [] snd_seq_timer_open+0xe7/0x130
 PGD 785cd067 PUD 76964067 PMD 0
 Oops: 0002 [#4] SMP
 CPU 0
 Pid: 4288, comm: trinity-child7 Tainted: G      D W 3.9.0-rc1+ #100 Bochs Bochs
 RIP: 0010:[]  [] snd_seq_timer_open+0xe7/0x130
 RSP: 0018:ffff88006ece7d38  EFLAGS: 00010246
 RAX: 0000000000000286 RBX: ffff88007851b400 RCX: 0000000000000000
 RDX: 000000000000ffff RSI: ffff88006ece7d58 RDI: ffff88006ece7d38
 RBP: ffff88006ece7d98 R08: 000000000000000a R09: 000000000000fffe
 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
 R13: ffff8800792c5400 R14: 0000000000e8f000 R15: 0000000000000007
 FS:  00007f7aaa650700(0000) GS:ffff88007f800000(0000) GS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00000000000002ae CR3: 000000006efec000 CR4: 00000000000006f0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
 Process trinity-child7 (pid: 4288, threadinfo ffff88006ece6000, task ffff880076a8a290)
 Stack:
  0000000000000286 ffffffff828f2be0 ffff88006ece7d58 ffffffff810f354d
  65636e6575716573 2065756575712072 ffff8800792c0030 0000000000000000
  ffff88006ece7d98 ffff8800792c5400 ffff88007851b400 ffff8800792c5520
 Call Trace:
  [] ? trace_hardirqs_on+0xd/0x10
  [] snd_seq_queue_timer_open+0x29/0x70
  [] snd_seq_ioctl_set_queue_timer+0xda/0x120
  [] snd_seq_do_ioctl+0x9b/0xd0
  [] snd_seq_ioctl+0x10/0x20
  [] do_vfs_ioctl+0x522/0x570
  [] ? file_has_perm+0x83/0xa0
  [] ? trace_hardirqs_on+0xd/0x10
  [] sys_ioctl+0x5d/0xa0
  [] ? trace_hardirqs_on_thunk+0x3a/0x3f
  [] system_call_fastpath+0x16/0x1b

Reported-and-tested-by: Tommi Rantala 
Cc: 
Signed-off-by: Takashi Iwai