Paul Coccoli wrote: > On Fri, Oct 17, 2008 at 8:46 AM, Paul Davis <paul@xxxxxxxxxxxxxxxxxxxxx> wrote: >> >> I'd rather add the memory barriers to the JACK code, but this could be a >> race to see who does what first. A memory barrier is typically single >> instruction. The complication tends to be defining them in a >> sufficiently portable way. > > Why do you suspect you need memory barriers? My concern with > ringbuffer.c is the non-atomic ops on the read and write pointers. > They're marked volatile, but what I think you really want is make all > ops on those fields atomic. Stuff like this: > > rb->read_ptr += n1; > rb->read_ptr &= rb->size_mask; > > Looks like a problem to me. What happens if there's a context switch > in between those 2 statements? > > NB: I only took a cursory glance at the code. Well, it looks like you had a fast but great insight here. I've turned all statements of this kind into one-liners, and the jack ringbuffer now (apparently) passes the test. Here's the patch against jack1 r3007: http://svn.samalyse.com/misc/rbtest/patches/jack-r3007-rb-fix.diff And thanks everyone for the tests ! I've updated the test suite, it now contains an additional test with this patch. Please continue testing :) -- Olivier Guilyardi / Samalyse _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/mailman/listinfo/linux-audio-user
