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Commit dc9b229a authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

genirq: Allow irq chips to mark themself oneshot safe 



Some interrupt chips like MSI are oneshot safe by implementation. For
those interrupts we can avoid the mask/unmask sequence for threaded
interrupt handlers.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1207132056540.32033@ionos
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Jan Kiszka <jan.kiszka@web.de>
parent e2b34e31

include/linux/irq.h

+1 −0
Original line number Diff line number Diff line
@@ -349,6 +349,7 @@ enum { 
	IRQCHIP_MASK_ON_SUSPEND		= (1 <<  2),

	IRQCHIP_ONOFFLINE_ENABLED	= (1 <<  3),

	IRQCHIP_SKIP_SET_WAKE		= (1 <<  4),

	IRQCHIP_ONESHOT_SAFE		= (1 <<  5),

};



/* This include will go away once we isolated irq_desc usage to core code */

kernel/irq/manage.c

+14 −1
Original line number Diff line number Diff line
@@ -959,6 +959,18 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new) 
		goto out_thread;

	}



	/*

	 * Drivers are often written to work w/o knowledge about the

	 * underlying irq chip implementation, so a request for a

	 * threaded irq without a primary hard irq context handler

	 * requires the ONESHOT flag to be set. Some irq chips like

	 * MSI based interrupts are per se one shot safe. Check the

	 * chip flags, so we can avoid the unmask dance at the end of

	 * the threaded handler for those.

	 */

	if (desc->irq_data.chip->flags & IRQCHIP_ONESHOT_SAFE)

		new->flags &= ~IRQF_ONESHOT;



	/*

	 * The following block of code has to be executed atomically

	 */
@@ -1033,7 +1045,8 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new) 
		 */

		new->thread_mask = 1 << ffz(thread_mask);



	} else if (new->handler == irq_default_primary_handler) {

	} else if (new->handler == irq_default_primary_handler &&

		   !(desc->irq_data.chip->flags & IRQCHIP_ONESHOT_SAFE)) {

		/*

		 * The interrupt was requested with handler = NULL, so

		 * we use the default primary handler for it. But it