Re: Question regarding mutex locking

["Bryan O'Sullivan" <bos@serpentine.com>]

Larry Finger wrote:
> If a particular routine needs to lock a mutex, but it may be entered with that mutex already locked,
> would the following code be SMP safe?
> 
> hold_lock = mutex_trylock()

The common way to deal with this is first to restructure your function 
into two.  One always acquires the lock, and the other (often written 
with a "__" prefix) never acquires it.  The never-acquire code does the 
actual work, and the always-acquire function calls it.

You then refactor the callers so that you don't have any code paths on 
which you can't predict whether or not the lock will be held.

	<b