svn commit: r339582 - head/sys/dev/sound/midi

Hans Petter Selasky hps at selasky.org
Mon Oct 22 10:27:20 UTC 2018


On 10/22/18 12:20 PM, Konstantin Belousov wrote:
> Then why do you need to re-acquire the mutex after uiomove ?

Hi,

Because the code is factored this way:

mtx_lock();
while (uio->uio_resid > 0) {
	do state checks()
	mtx_unlock();
	retval = uiomove();
	mtx_lock();
}
mtx_unlock();

Yes, you're right the last mtx_lock() can be optimised away. I'm leaving 
that to somebody else. This code typically is processing MIDI events at 
very slow rates like 8KBytes/s and does not need to be very fast.

--HPS


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