Re: [ANNOUNCE] v4.11.5-rt1

[Sebastian Andrzej Siewior]

On 2017-06-20 09:45:06 [+0200], Mike Galbraith wrote:
> See ! and ?

See see.
What about this:

diff --git a/include/linux/sched.h b/include/linux/sched.h
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1014,8 +1014,20 @@ struct wake_q_head {
 #define WAKE_Q(name)                                   \
        struct wake_q_head name = { WAKE_Q_TAIL, &name.first }
 
-extern void wake_q_add(struct wake_q_head *head,
-                             struct task_struct *task);
+extern void __wake_q_add(struct wake_q_head *head,
+                        struct task_struct *task, bool sleeper);
+static inline void wake_q_add(struct wake_q_head *head,
+                             struct task_struct *task)
+{
+       __wake_q_add(head, task, false);
+}
+
+static inline void wake_q_add_sleeper(struct wake_q_head *head,
+                                     struct task_struct *task)
+{
+       __wake_q_add(head, task, true);
+}
+
 extern void __wake_up_q(struct wake_q_head *head, bool sleeper);
 
 static inline void wake_up_q(struct wake_q_head *head)
@@ -1745,6 +1757,7 @@ struct task_struct {
        raw_spinlock_t pi_lock;
 
        struct wake_q_node wake_q;
+       struct wake_q_node wake_q_sleeper;
 
 #ifdef CONFIG_RT_MUTEXES
        /* PI waiters blocked on a rt_mutex held by this task */
diff --git a/kernel/fork.c b/kernel/fork.c
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -558,6 +558,7 @@ static struct task_struct *dup_task_struct(struct 
task_struct *orig, int node)
        tsk->splice_pipe = NULL;
        tsk->task_frag.page = NULL;
        tsk->wake_q.next = NULL;
+       tsk->wake_q_sleeper.next = NULL;
 
        account_kernel_stack(tsk, 1);
 
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1506,7 +1506,7 @@ static void mark_wakeup_next_waiter(struct wake_q_head 
*wake_q,
         */
        preempt_disable();
        if (waiter->savestate)
-               wake_q_add(wake_sleeper_q, waiter->task);
+               wake_q_add_sleeper(wake_sleeper_q, waiter->task);
        else
                wake_q_add(wake_q, waiter->task);
        raw_spin_unlock(&current->pi_lock);
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -430,9 +430,15 @@ static bool set_nr_if_polling(struct task_struct *p)
 #endif
 #endif
 
-void wake_q_add(struct wake_q_head *head, struct task_struct *task)
+void __wake_q_add(struct wake_q_head *head, struct task_struct *task,
+                 bool sleeper)
 {
-       struct wake_q_node *node = &task->wake_q;
+       struct wake_q_node *node;
+
+       if (sleeper)
+               node = &task->wake_q_sleeper;
+       else
+               node = &task->wake_q;
 
        /*
         * Atomically grab the task, if ->wake_q is !nil already it means
@@ -461,11 +467,17 @@ void __wake_up_q(struct wake_q_head *head, bool sleeper)
        while (node != WAKE_Q_TAIL) {
                struct task_struct *task;
 
-               task = container_of(node, struct task_struct, wake_q);
+               if (sleeper)
+                       task = container_of(node, struct task_struct, 
wake_q_sleeper);
+               else
+                       task = container_of(node, struct task_struct, wake_q);
                BUG_ON(!task);
                /* task can safely be re-inserted now */
                node = node->next;
-               task->wake_q.next = NULL;
+               if (sleeper)
+                       task->wake_q_sleeper.next = NULL;
+               else
+                       task->wake_q.next = NULL;
 
                /*
                 * wake_up_process() implies a wmb() to pair with the queueing