priority inherence bug?

Manuel manuel.coutinho at
Wed Dec 3 11:51:25 UTC 2008


We are doing some tests to RTEMS and have stumbled in a possible bug when
semaphores with priority inherence are used.

Suppose a low priority task obtains two semaphores with priority inherence.
After it obtains the critical region, other higher priority tasks also try
to obtain the semaphores.
We have tested that the priority of the lower priority task is correctly
raised to the priority of the highest priority task that tries to obtain the
semaphore. However, when the low priority task releases the first semaphore,
its priority should decrease (because the second semaphore is only used by
middle priority tasks). The priority of the lower priority task is only
restored to its original when it released the two semaphores.

In our opinion, this is not the correct behavior of priority inherence
semaphores. We will try to correct this bug.

Kind regards
Manuel Coutinho

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