From: Christoph Hellwig <hch@lst.de>
Subject: [PATCH] shaper.c: fix locking
Date: Fri, 27 May 2005 13:54:50 +0200

 o use a semaphore instead of an opencoded and racy lock
 o move locking out of shaper_kick and into the callers - most just
   released the lock before calling shaper_kick
 o remove in_interrupt() tests.  from ->close we can always block, from
   ->hard_start_xmit and timer context never

Do you really want to use a semaphore for a lock taken
%99 of the time in software IRQ context, which obviously
cannot sleep?