Commit 4bcdf1d0 authored by Alexander Gordeev's avatar Alexander Gordeev Committed by Thomas Gleixner
Browse files

genirq: Get rid of unnecessary irqaction field in task_struct 



When a new thread handler is created, an irqaction is passed to it as
data. Not only that irqaction is stored in task_struct by the handler
for later use, but also a structure associated with the kernel thread
keeps this value as long as the thread exists.

This fix kicks irqaction out off task_struct. Yes, I introduce new bit
field. But it allows not only to eliminate the duplicate, but also
shortens size of task_struct.

Reported-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarAlexander Gordeev <agordeev@redhat.com>
Link: http://lkml.kernel.org/r/20120309135925.GB2114@dhcp-26-207.brq.redhat.com


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 540b60e2

include/linux/sched.h

+5 −5
Original line number Diff line number Diff line
@@ -1319,6 +1319,11 @@ struct task_struct { 
	unsigned sched_reset_on_fork:1;

	unsigned sched_contributes_to_load:1;



#ifdef CONFIG_GENERIC_HARDIRQS

	/* IRQ handler threads */

	unsigned irq_thread:1;

#endif



	pid_t pid;

	pid_t tgid;
@@ -1427,11 +1432,6 @@ struct task_struct { 
 * mempolicy */

	spinlock_t alloc_lock;



#ifdef CONFIG_GENERIC_HARDIRQS

	/* IRQ handler threads */

	struct irqaction *irqaction;

#endif



	/* Protection of the PI data structures: */

	raw_spinlock_t pi_lock;

kernel/irq/manage.c

+11 −8
Original line number Diff line number Diff line
@@ -780,7 +780,7 @@ static int irq_thread(void *data) 
		handler_fn = irq_thread_fn;



	sched_setscheduler(current, SCHED_FIFO, &param);

	current->irqaction = action;

	current->irq_thread = 1;



	while (!irq_wait_for_interrupt(action)) {
@@ -818,10 +818,10 @@ static int irq_thread(void *data) 
	irq_finalize_oneshot(desc, action, true);



	/*

	 * Clear irqaction. Otherwise exit_irq_thread() would make

	 * Clear irq_thread. Otherwise exit_irq_thread() would make

	 * fuzz about an active irq thread going into nirvana.

	 */

	current->irqaction = NULL;

	current->irq_thread = 0;

	return 0;

}
@@ -832,27 +832,30 @@ void exit_irq_thread(void) 
{

	struct task_struct *tsk = current;

	struct irq_desc *desc;

	struct irqaction *action;



	if (!tsk->irqaction)

	if (!tsk->irq_thread)

		return;



	action = kthread_data(tsk);



	printk(KERN_ERR

	       "exiting task \"%s\" (%d) is an active IRQ thread (irq %d)\n",

	       tsk->comm ? tsk->comm : "", tsk->pid, tsk->irqaction->irq);

	       tsk->comm ? tsk->comm : "", tsk->pid, action->irq);



	desc = irq_to_desc(tsk->irqaction->irq);

	desc = irq_to_desc(action->irq);



	/*

	 * Prevent a stale desc->threads_oneshot. Must be called

	 * before setting the IRQTF_DIED flag.

	 */

	irq_finalize_oneshot(desc, tsk->irqaction, true);

	irq_finalize_oneshot(desc, action, true);



	/*

	 * Set the THREAD DIED flag to prevent further wakeups of the

	 * soon to be gone threaded handler.

	 */

	set_bit(IRQTF_DIED, &tsk->irqaction->flags);

	set_bit(IRQTF_DIED, &action->flags);

}



static void irq_setup_forced_threading(struct irqaction *new)

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