4 <TITLE>Priority Inversion Protocol</TITLE>

     4 <TITLE>HGMP</TITLE>

     5 <BASE HREF="http://www.dcs.kcl.ac.uk/staff/urbanc/">

     5 <BASE HREF="http://www.inf.kcl.ac.uk/staff/urbanc/">

    25 <H2>Proving the Priority Inheritance Protocol Correct</H2>

    25 <H2>Modelling homogeneous generative meta-programming: Artefact</H2>

    27 By Xingyuan Zhang, Christian Urban and Chunhan Wu

    27 Martin Berger, Laurence Tratt, Christian Urban

    29 In real-time systems with threads, resource locking and 

    29 <ul>

    30 priority scheduling, one faces the problem of Priority

    30 <li>1. Download Isabelle

    31 Inversion. This problem can make the behaviour of threads

    31 </u>

    32 unpredictable and the resulting bugs can be hard to find.  The

    33 Priority Inheritance Protocol is one solution implemented in many

    34 systems for solving this problem, but the correctness of this solution

    35 has never been formally verified in a theorem prover. As already

    36 pointed out in the literature, the original informal investigation of

    37 the Property Inheritance Protocol presents a correctness "proof" for

    38 an incorrect algorithm. In this paper we fix the problem of

    39 this proof by making all notions precise and implementing a variant of

    40 a solution proposed earlier. Our formalisation in Isabelle/HOL

    41 uncovers facts not mentioned in the literature, but also shows how to

    42 efficiently implement this protocol. Earlier correct implementations

    43 were criticised as too inefficient. Our formalisation is based on

    44 Paulson's inductive approach to verifying protocols.

    45 <BR><BR>

    47 The source code can be downloaded 

    33 

    48 <A HREF="http://www4.in.tum.de/~urbanc/cgi-bin/repos.cgi/prio">here</A>.

    49 <BR><BR><BR><BR>