Mutexes were added in 2.6.16. This will allow future changes to use the mutex API without breaking on pre 2.6.16 kernels. Signed-off-by: Shaun Ruffell <sruffell@digium.com> Acked-by: Kinsey Moore <kmoore@digium.com> Origin: http://svnview.digium.com/svn/dahdi?view=rev&rev=9579 git-svn-id: http://svn.asterisk.org/svn/dahdi/linux/branches/2.4@9690 a0bf4364-ded3-4de4-8d8a-66a801d63aff