Posted Mar 21, 2008 20:02 UTC (Fri) by Alan.Stern (subscriber, #12437)
Parent article: Generic semaphores
One reason for keeping semaphores around is that they aren't subject to lockdep checking,
whereas mutexes are. While this checking is a very good thing and I'm all in favor of it, the
fact remains that there are some usage patterns lockdep cannot handle. A typical example is a
tree of data structures (like the device tree), where locks must be acquired from the top
down, or from the bottom up.