>From: David Singleton > > Here is a set of patches that implement robust futexes with > priority queuing and priority inheritance on a per futex basis > for the 2.6.13 kernel. > > Priority queuing and priority inheritance for robust futexes > are implemented using the rt_mutex structure, which nicely >handles the > priority queuing and inheritance features. The rt_mutex structure > has been extended to allow priority inheritance on a per mutex
I need to see this applied to a tree, because the patch is kind of difficult to follow if not; however, a few tidbits: * In the common_robust_pi patch, in futex_wait_robust() at the end of the function: isn't find_task_by_pid() to be protected with the task list lock? [I don't remember for sure]. * I still find that forcing a mutex interface through a queue interface is An Ugly And Cumbersome Hack (tm) and will come back to bite us in the future. We should be sticking to maintain the futex interface like it is for compatibility and simple mutexes/waitqueues and create a new mutex interface with all the new features. * How do you avoid the race conditions in the unlock path when fast path is enabled? It is not to clear to me what are the fast path rules--again this could also be because I wasn't able to apply this to a tree and see the whole picture. -- Inaky
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