[PATCH 4/4] score: Use Resource Handler for MrsP semaphores

[Sebastian Huber]

On 2014-06-03 16:14, Gedare Bloom wrote:
> On Tue, Jun 3, 2014 at 6:55 AM, Sebastian Huber
> <sebastian.huber at embedded-brains.de>  wrote:
>> >
>> >I think the bigger problem is that the priority inheritance affects only one
>> >level, see new test sptests/spsem03.
>> >
>> >
> Is there a bug PR associated with this test? The behavior under test
> looks like a bug to me.

I don't know how old the priority inheritance implementation is in RTEMS, but I 
guess it is very old.  So this is probably not a bug, its a feature.

With the simple resource count base implementation I think it is impossible to 
recursively walk though the resource dependency tree.  You would have to use 
object specific information (for example CORE_mutex_Control::holder) which is 
difficult to access from object agnostic routines.

I want to address these issues with the Resource Handler for the MrsP 
semaphores.  See diagram here:

http://www.rtems.org/onlinedocs/doxygen/cpukit/html/group__ScoreResource.html

Lets suppose all the resources r0 up to r15 are MrsP semaphores, then the owner 
n0 of the resource tree can execute using (= scheduler instance + priority) all 
the n1 up to n15 nodes (= threads waiting for resource access).

-- 
Sebastian Huber, embedded brains GmbH

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