From: Ivo Sieben <meltedpianoman@xxxxxxxxx> 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. Cc: stable-rt@xxxxxxxxxxxxxxx Signed-off-by: Ivo Sieben <meltedpianoman@xxxxxxxxx> Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Link: http://lkml.kernel.org/r/1370254322-17240-1-git-send-email-meltedpianoman@xxxxxxxxx Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> --- kernel/irq/manage.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index 22ca55a..ff54ceb 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -797,9 +797,6 @@ static void wake_threads_waitq(struct irq_desc *desc) */ static int irq_thread(void *data) { - 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, @@ -811,7 +808,6 @@ static int irq_thread(void *data) else handler_fn = irq_thread_fn; - sched_setscheduler(current, SCHED_FIFO, ¶m); current->irq_thread = 1; while (!irq_wait_for_interrupt(action)) { @@ -944,6 +940,9 @@ __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); @@ -951,6 +950,9 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new) ret = PTR_ERR(t); goto out_mput; } + + sched_setscheduler(t, SCHED_FIFO, ¶m); + /* * We keep the reference to the task struct even if * the thread dies to avoid that the interrupt code -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe stable-rt" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
