Messages in this thread | | | Subject | RE: [PATCH] Abstracted Priority Inheritance for RT | Date | Wed, 1 Jun 2005 17:10:04 -0700 | From | "Perez-Gonzalez, Inaky" <> |
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>From: Daniel Walker [mailto:dwalker@mvista.com] >On Wed, 2005-06-01 at 16:07 +0200, Esben Nielsen wrote: > >> Do you plan to use that callback for priority inheritance? >> If so: It would lead to an recursive algorithm. That is not very nice in >> the kernel with a limited call-stack. It is not so much a problem if the >> mechanism is used in the kernel only, but if it is used for user-space >> locking, which can have unlimited neesting, it is potential problem. > >There is an API for for priority inheritance, the call by is strictly >for the PI mechanism to signal when it changes a waiters priority , as >the result of PI. > >It's somewhat explained in linux/pi.h . Currently the rt_mutex uses this >callback to move the waiter depending on it's new priority. > >I'm not sure I see how this could become recursive, could you explain >more?
Maybe he is referring to the case?
A owns M B owns N and is waiting for M A is trying to wait for N
These deadlocking cases can be tricky during PI.
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