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DragonFly bugs List (threaded) for 2006-05
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Re: Missing symbol in lwkt_thread.c

From: Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>
Date: Fri, 19 May 2006 10:48:15 -0700 (PDT)

:lwkt_relalltokens is defined in thread.h, but because
:of an #ifdef in lwkt_thread.c, thread2.h is included
:instead of thread.h.  Are these backwards in the #ifdef?

   Ouch.  It's a bit more complicated then I originally thought.  Or
   actually, less complicated then I thought. 

   The token code still has the same semantics as it did before, but 
   on SMP systems I am using an active spinlock now instead of a 
   passive per-cpu lock.  When I originally coded it I forgot that
   the spinlock routines would not work as interlocks on UP builds
   (because they are just degenerate NOPs on UP builds).

   But, at the same time, on a UP system there is no need to track tokens
   on a per-thread basis and no need to have a spinlock or even *DO*
   anything when a thread switch occurs.  Since by definition a held token
   is only 'active' when the thread holding it is running, the only thing
   that is needed on a UP system is to check whether a token is being held
   by a preempted thread.  Neither lwkt_getalltokens() or lwkt_relalltokens()
   needs to be called at all on a UP system.

   I am cleaning it all up now and will commit a fix shortly.

					Matthew Dillon 

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