Messages in this thread | | | Subject | Re: [PATCH 1/19] MUTEX: Introduce simple mutex implementation | From | Steven Rostedt <> | Date | Thu, 15 Dec 2005 16:28:15 -0500 |
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On Thu, 2005-12-15 at 12:18 -0800, Andrew Morton wrote: > Andrew Morton <akpm@osdl.org> wrote: > > > > David Howells <dhowells@redhat.com> wrote: > > > > > > So... Would you then object to an implementation of a mutex appearing in the > > > tree which semaphores that are being used as strict mutexes can be migrated > > > over to as the opportunity arises? > > > > That would be sane. > > > > But not very. > > Look at it from the POV of major architectures: there's no way the new > mutex code will be faster than down() and up(), so we're adding a bunch of > new tricky locking code which bloats the kernel and has to be understood > and debugged for no gain.
I see it as a stepping stone for RT ;)
> > And I don't buy the debuggability argument really. It'd be pretty simple > to add debug code to the existing semaphore code to trap non-mutex usages. > Then go through the few valid non-mutex users and do: > > #if debug > sem->this_is_not_a_mutex = 1; > #endif
That just looks plain ugly. Still, if you want to keep the major archs unchanged (at least until RT is in!) then just add the following:
#define mutex_lock(x) down(x) #define mutex_unlock(x) up(x) #define mutex_trylock(x) (!down_trylock(x)) /* see previous email! */
Then you can add your ugly patch ;) where on debug we define those declared with DEFINE_SEM(x) add the this_is_not_a_mutex = 1
-- Steve
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