From fb00aca474405f4fa8a8519c3179fed722eabd83 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 7 Nov 2013 14:43:43 +0100 Subject: rtmutex: Turn the plist into an rb-tree Turn the pi-chains from plist to rb-tree, in the rt_mutex code, and provide a proper comparison function for -deadline and -priority tasks. This is done mainly because: - classical prio field of the plist is just an int, which might not be enough for representing a deadline; - manipulating such a list would become O(nr_deadline_tasks), which might be to much, as the number of -deadline task increases. Therefore, an rb-tree is used, and tasks are queued in it according to the following logic: - among two -priority (i.e., SCHED_BATCH/OTHER/RR/FIFO) tasks, the one with the higher (lower, actually!) prio wins; - among a -priority and a -deadline task, the latter always wins; - among two -deadline tasks, the one with the earliest deadline wins. Queueing and dequeueing functions are changed accordingly, for both the list of a task's pi-waiters and the list of tasks blocked on a pi-lock. Signed-off-by: Peter Zijlstra Signed-off-by: Dario Faggioli Signed-off-by: Juri Lelli Signed-off-again-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1383831828-15501-10-git-send-email-juri.lelli@gmail.com Signed-off-by: Ingo Molnar --- kernel/futex.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'kernel/futex.c') diff --git a/kernel/futex.c b/kernel/futex.c index f6ff0191ecf7..679531c61d96 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -2316,6 +2316,8 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags, * code while we sleep on uaddr. */ debug_rt_mutex_init_waiter(&rt_waiter); + RB_CLEAR_NODE(&rt_waiter.pi_tree_entry); + RB_CLEAR_NODE(&rt_waiter.tree_entry); rt_waiter.task = NULL; ret = get_futex_key(uaddr2, flags & FLAGS_SHARED, &key2, VERIFY_WRITE); -- cgit v1.2.3