Messages in this thread | | | From | Keith Owens <> | Subject | Re: [PATCH for 2.5] preemptible kernel | Date | Wed, 21 Mar 2001 20:04:57 +1100 |
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On Wed, 21 Mar 2001 00:04:56 -0800, george anzinger <george@mvista.com> wrote: >Exactly so. The method does not depend on the sum of preemption being >zip, but on each potential reader (writers take locks) passing thru a >"sync point". Your notion of waiting for each task to arrive >"naturally" at schedule() would work. It is, in fact, over kill as you >could also add arrival at sys call exit as a (the) "sync point". In >fact, for module unload, isn't this the real "sync point"? After all, a >module can call schedule, or did I miss a usage counter somewhere?
A module can call schedule but it must do MOD_INC_USE_COUNT first. Sleeping in module code without incrementing the module use count first is a shooting offence. It is so full of races that you may as well call it Daytona.
>By the way, there is a paper on this somewhere on the web. Anyone >remember where?
http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf
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