cvs commit: src/sys/kern kern_umtx.c src/sys/sys umtx.h

Nate Lawson nate at
Mon Mar 31 17:34:21 PST 2003

On Mon, 31 Mar 2003, Jeff Roberson wrote:
>   Added files:
>     sys/kern             kern_umtx.c 
>     sys/sys              umtx.h 
>   Log:
>    - Add an api for doing smp safe locks in userland.
>    - umtx_lock() is defined as an inline in umtx.h.  It tries to do an
>      uncontested acquire of a lock which falls back to the _umtx_lock()
>      system-call if that fails.
>    - umtx_unlock() is also an inline which falls back to _umtx_unlock() if the
>      uncontested unlock fails.
>    - Locks are keyed off of the thr_id_t of the currently running thread which
>      is currently just the pointer to the 'struct thread' in kernel.
>    - _umtx_lock() uses the proc pointer to synchronize access to blocked thread
>      queues which are stored in the first blocked thread.
>   Revision  Changes    Path
>   1.1       +303 -0    src/sys/kern/kern_umtx.c (new)
>   1.1       +87 -0     src/sys/sys/umtx.h (new)

It's great to be getting this.  Can you point me to a document indicating
how this will be used by KSE?  Are we going to have "native threads"
(thr), KSE, and pthreads?


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