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From: John Baldwin <jhb@FreeBSD.org>
To: Perforce Change Reviews <perforce@freebsd.org>
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Subject: PERFORCE change 84453 for review
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http://perforce.freebsd.org/chv.cgi?CH=84453

Change 84453 by jhb@jhb_slimer on 2005/09/28 20:25:08

	Not a race.  el_runcount already handles this.

Affected files ...

.. //depot/projects/smpng/sys/notes#60 edit

Differences ...

==== //depot/projects/smpng/sys/notes#60 (text+ko) ====

@@ -75,49 +75,6 @@
     - arm, powerpc?
   - fork counts?
 - Add a cache-line padded mtx_aligned union and use it for the mutex pools.
-- Fix free race in eventhandlers:
-> In the macro "_EVENTHANDLER_INVOKE" in the file
-> "/sys/sys/eventhandler.h", you unlock the list lock
-> before calling the callback. That make sense. But what
-> happens if one process is in the callback, and another
-> process is deregistering this tag.
->
-> The solution is that the last thread
-> that has anything to do with a entry
-> frees it:
->
-> TAILQ_FOREACH()
-> {
->  refcount++;
->
->  EHL_UNLOCK();
->
->  callback();
->
->  EHL_LOCK();
->
->  refcount--;
->
->  if(refcount == 0)
->    free(entry);
-> }
->
-> At init:
->  refcount = 1;
->
->
-> At deregister:
->
-> EHL_LOCK();
->
-> refcount--;
-> if(refcount == 0)
->   free();
->
-> EHL_UNLOCK();
->
-> --HPS
->
 
 Active child branches:
 - jhb_intr - intr_event stuff