genirq: Set irq thread to RT priority on creation (ee238713) · Commits · 戴 / test

When a threaded irq handler is installed the irq thread is initially created on normal scheduling priority. Only after the irq thread is woken up it sets its priority to RT_FIFO MAX_USER_RT_PRIO/2 itself. This means that interrupts that occur directly after the irq handler is installed will be handled on a normal scheduling priority instead of the realtime priority that one would expect. Fix this by setting the RT priority on creation of the irq_thread. Signed-off-by:

Ivo Sieben <meltedpianoman@gmail.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/1370254322-17240-1-git-send-email-meltedpianoman@gmail.com Signed-off-by:

Thomas Gleixner <tglx@linutronix.de>

kernel/irq/manage.c

+6 −5

Original line number	Diff line number	Diff line
		@@ -840,9 +840,6 @@ static void irq_thread_dtor(struct callback_head *unused)
		static int irq_thread(void *data)
		{
		struct callback_head on_exit_work;
		static const struct sched_param param = {
		.sched_priority = MAX_USER_RT_PRIO/2,
		};
		struct irqaction *action = data;
		struct irq_desc *desc = irq_to_desc(action->irq);
		irqreturn_t (handler_fn)(struct irq_desc desc,
		@@ -854,8 +851,6 @@ static int irq_thread(void *data)
		else
		handler_fn = irq_thread_fn;

		sched_setscheduler(current, SCHED_FIFO, &param);

		init_task_work(&on_exit_work, irq_thread_dtor);
		task_work_add(current, &on_exit_work, false);

		@@ -950,6 +945,9 @@ __setup_irq(unsigned int irq, struct irq_desc desc, struct irqaction new)
		*/
		if (new->thread_fn && !nested) {
		struct task_struct *t;
		static const struct sched_param param = {
		.sched_priority = MAX_USER_RT_PRIO/2,
		};

		t = kthread_create(irq_thread, new, "irq/%d-%s", irq,
		new->name);
		@@ -957,6 +955,9 @@ __setup_irq(unsigned int irq, struct irq_desc desc, struct irqaction new)
		ret = PTR_ERR(t);
		goto out_mput;
		}

		sched_setscheduler(t, SCHED_FIFO, &param);

		/*
		* We keep the reference to the task struct even if
		* the thread dies to avoid that the interrupt code

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