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Date: Sun, 1 Oct 2006 13:36:31 +0200 (CEST) From: Esben Nielsen <nielsen.esben@...glemail.com> To: Ingo Molnar <mingo@...e.hu> cc: linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>, Steven Rostedt <rostedt@...dmis.org> Subject: [patch 0/5] Fix timeout bug in rtmutex in 2.6.18-rt Hi, I finally got around to merge my patches into a newer -rt kernel and repost them. To refresh: pthread_mutex_timedlock() for PI-futexes doesn't work on a UP machine: Task A tries to take a lock with a timeout of say 1 ms. This lock is owned by B which is boosted to task A's priority. The timeout interrupt wakes up A, but since B is already running at A's priority, A will not get any CPU before B unlocks the lock anyway. This series of patches does the following: 1) It adds an interface to the scheduler such that task A is woken up LIFO instead of FIFO. That means that A is now preempting B even though they have the same priority. Thus A can de-boost B and exit the pthread_mutex_timedlock() before B is done with the lock. 2) This is a smaller update to the rt-mutex-tester scripts. Probably not needed, I'll post it anyway. 3) This patch makes sure that A will not loose it's priority while boosting B. In case of other PI-mutex operations touches A's priority or explicit setscheduler() calls, A will not actually loose it's priority. That is postponed until A leaves the lock operation (successfully or not). Thus A will always be able to de-boost B. 4) Is a documentation update. 5) Is a fix to the PI-futex: There is (still) lacking a protection for the rtmutex's internal state because. It might not be the cleanest way to do this. Esben -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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