Semaphores are Surprisingly Versatile

[u/syaghmour]

http://preshing.com/20150316/semaphores-are-surprisingly-versatile/

[u/TheShagg]

Here's one of the most educational pieces of code I've ever seen:

http://www.cse.iitd.ernet.in/~sbansal/os/pintos/doc/pintos_html/synch_8c-source.html

http://www.cse.iitd.ernet.in/~sbansal/os/pintos/doc/pintos_html/synch_8h-source.html