Thanks a lot for looking further into this. I'd like to join the fun in
removing the rest of the semaphores in the kernel, but with you, Ingo,
Daniel and Jon going to do that, one more cook will just spoil the stew.
Once we get rid of all the semaphores in the kernel that are being used as
mutexes, then we can change the code in the -rt patch to keep semaphores
default as compat_semaphores. And any out of tree driver would just need
to be fixed to use mutexes.
Well, read/write semaphores might have to stay special.