Shared dataspace problem

Frank Mehnert fm3 at os.inf.tu-dresden.de
Tue Jul 19 17:15:54 CEST 2005


Hi Leon,

On Tuesday 19 July 2005 17:05, Leon Brits wrote:
> I have a dataspace, reserved as pool 1 by dm_phys, which two tasks
> shares. They synchronise access to the data by setting a lock at the
> start of the dataspace with a cmpxchg-loop. All tasks map the dataspace
> to their own VM area.
>
> The problem is that if one of the tasks exists then the other would stop
> with a page fault error the next time it accesses the shared dataspace.
> Both of them where happily reading and writing to the dataspace at
> exactly the place where the page fault occur.

Hmm, that might be a bug in the resource de-allocation function of
dm_phys. I assume that you use the event-server, don't you? In this
case, all resources (names, dataspaces, ...) bound to a task are
freed at exit of the task. Which task exits? The task which allocated
the dataspace or the other?

Frank
-- 
## Dept. of Computer Science, Dresden University of Technology, Germany ##
## http://os.inf.tu-dresden.de/~fm3                                     ##
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