CVS commit: src/sys/dev/audio

["Taylor R Campbell" <riastradh%netbsd.org@localhost>]

Module Name:    src
Committed By:   riastradh
Date:           Mon Mar 14 11:47:34 UTC 2022

Modified Files:
        src/sys/dev/audio: audio.c

Log Message:
audio(4): Membar audit.

Won't affect anything on x86 because atomic r/m/w operations are
always full sequential consistency barriers, but might potentially
fix problems on, e.g., arm.

Note 1: I'm not clear on why the track lock is a bespoke mutex made
out of an atomic -- why not just mutex(9)?

Note 2: I'm not convinced the audio_mlog_flush synchronization is
correct; what happens if the softint runs on two CPUs at the same
time and swaps mlog_wpage simultaneously?

Note 3: Should maybe use atomic_load/store_relaxed for mlog_full and
mlog_drop, and atomic_inc/dec for mlog_refs.


To generate a diff of this commit:
cvs rdiff -u -r1.113 -r1.114 src/sys/dev/audio/audio.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.