iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

ALSA: seq_timer: use monotonic times internally

Browse Source 
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 <arnd@arndb.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Arnd Bergmann
2016-06-17 17:10:32 +02:00
committed by Takashi Iwai
parent d169133889
commit 3915bf2946
2 changed files with 10 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
sound/core/seq/seq_timer.h
View File

@ -52,7 +52,7 @@ struct snd_seq_timer {
unsigned int skew;
unsigned int skew_base;
struct timeval last_update; /* time of last clock update, used for interpolation */
struct timespec64 last_update; /* time of last clock update, used for interpolation */
spinlock_t lock;
};