From 68e34f4e89e2bb64d53e77a18e0cfddc3c7f24e9 Mon Sep 17 00:00:00 2001 From: Jonathan Haws Date: Tue, 6 Feb 2018 15:40:52 -0800 Subject: [PATCH] ipc/mqueue.c: have RT tasks queue in by priority in wq_add() Previous behavior added tasks to the work queue using the static_prio value instead of the dynamic priority value in prio. This caused RT tasks to be added to the work queue in a FIFO manner rather than by priority. Normal tasks were handled by priority. This fix utilizes the dynamic priority of the task to ensure that both RT and normal tasks are added to the work queue in priority order. Utilizing the dynamic priority (prio) rather than the base priority (normal_prio) was chosen to ensure that if a task had a boosted priority when it was added to the work queue, it would be woken sooner to to ensure that it releases any other locks it may be holding in a more timely manner. It is understood that the task could have a lower priority when it wakes than when it was added to the queue in this (unlikely) case. Link: http://lkml.kernel.org/r/1513006652-7014-1-git-send-email-jhaws@sdl.usu.edu Signed-off-by: Jonathan Haws Reviewed-by: Steven Rostedt (VMware) Reviewed-by: Davidlohr Bueso Cc: Ingo Molnar Cc: Al Viro Cc: Arnd Bergmann Cc: Deepa Dinamani Cc: Thomas Gleixner Cc: Sebastian Andrzej Siewior Cc: Manfred Spraul Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- ipc/mqueue.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/ipc/mqueue.c b/ipc/mqueue.c index 690ae6665500..360e564ae7d1 100644 --- a/ipc/mqueue.c +++ b/ipc/mqueue.c @@ -596,7 +596,7 @@ static void wq_add(struct mqueue_inode_info *info, int sr, ewp->task = current; list_for_each_entry(walk, &info->e_wait_q[sr].list, list) { - if (walk->task->static_prio <= current->static_prio) { + if (walk->task->prio <= current->prio) { list_add_tail(&ewp->list, &walk->list); return; }