Commit e360adbe authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

irq_work: Add generic hardirq context callbacks 



Provide a mechanism that allows running code in IRQ context. It is
most useful for NMI code that needs to interact with the rest of the
system -- like wakeup a task to drain buffers.

Perf currently has such a mechanism, so extract that and provide it as
a generic feature, independent of perf so that others may also
benefit.

The IRQ context callback is generated through self-IPIs where
possible, or on architectures like powerpc the decrementer (the
built-in timer facility) is set to generate an interrupt immediately.

Architectures that don't have anything like this get to do with a
callback from the timer tick. These architectures can call
irq_work_run() at the tail of any IRQ handlers that might enqueue such
work (like the perf IRQ handler) to avoid undue latencies in
processing the work.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: default avatarKyle McMartin <kyle@mcmartin.ca>
Acked-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
[ various fixes ]
Signed-off-by: default avatarHuang Ying <ying.huang@intel.com>
LKML-Reference: <1287036094.7768.291.camel@yhuang-dev>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 8e5fc1a7

arch/alpha/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ config ALPHA 
	select HAVE_IDE

	select HAVE_OPROFILE

	select HAVE_SYSCALL_WRAPPERS

	select HAVE_IRQ_WORK

	select HAVE_PERF_EVENTS

	select HAVE_DMA_ATTRS

	help

arch/alpha/include/asm/perf_event.h

+0 −5
Original line number Diff line number Diff line 
#ifndef __ASM_ALPHA_PERF_EVENT_H

#define __ASM_ALPHA_PERF_EVENT_H



/* Alpha only supports software events through this interface. */

extern void set_perf_event_pending(void);



#define PERF_EVENT_INDEX_OFFSET 0



#ifdef CONFIG_PERF_EVENTS

extern void init_hw_perf_events(void);

#else

arch/alpha/kernel/time.c

+15 −15
Original line number Diff line number Diff line
@@ -41,7 +41,7 @@ 
#include <linux/init.h>

#include <linux/bcd.h>

#include <linux/profile.h>

#include <linux/perf_event.h>

#include <linux/irq_work.h>



#include <asm/uaccess.h>

#include <asm/io.h>
@@ -83,25 +83,25 @@ static struct { 


unsigned long est_cycle_freq;



#ifdef CONFIG_PERF_EVENTS

#ifdef CONFIG_IRQ_WORK



DEFINE_PER_CPU(u8, perf_event_pending);

DEFINE_PER_CPU(u8, irq_work_pending);



#define set_perf_event_pending_flag()  __get_cpu_var(perf_event_pending) = 1

#define test_perf_event_pending()      __get_cpu_var(perf_event_pending)

#define clear_perf_event_pending()     __get_cpu_var(perf_event_pending) = 0

#define set_irq_work_pending_flag()  __get_cpu_var(irq_work_pending) = 1

#define test_irq_work_pending()      __get_cpu_var(irq_work_pending)

#define clear_irq_work_pending()     __get_cpu_var(irq_work_pending) = 0



void set_perf_event_pending(void)

void set_irq_work_pending(void)

{

	set_perf_event_pending_flag();

	set_irq_work_pending_flag();

}



#else  /* CONFIG_PERF_EVENTS */

#else  /* CONFIG_IRQ_WORK */



#define test_perf_event_pending()      0

#define clear_perf_event_pending()

#define test_irq_work_pending()      0

#define clear_irq_work_pending()



#endif /* CONFIG_PERF_EVENTS */

#endif /* CONFIG_IRQ_WORK */





static inline __u32 rpcc(void)
@@ -191,9 +191,9 @@ irqreturn_t timer_interrupt(int irq, void *dev) 


	write_sequnlock(&xtime_lock);



	if (test_perf_event_pending()) {

		clear_perf_event_pending();

		perf_event_do_pending();

	if (test_irq_work_pending()) {

		clear_irq_work_pending();

		irq_work_run();

	}



#ifndef CONFIG_SMP

arch/arm/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ config ARM 
	select HAVE_KERNEL_GZIP

	select HAVE_KERNEL_LZO

	select HAVE_KERNEL_LZMA

	select HAVE_IRQ_WORK

	select HAVE_PERF_EVENTS

	select PERF_USE_VMALLOC

	select HAVE_REGS_AND_STACK_ACCESS_API

arch/arm/include/asm/perf_event.h

+0 −12
Original line number Diff line number Diff line
@@ -12,18 +12,6 @@ 
#ifndef __ARM_PERF_EVENT_H__

#define __ARM_PERF_EVENT_H__



/*

 * NOP: on *most* (read: all supported) ARM platforms, the performance

 * counter interrupts are regular interrupts and not an NMI. This

 * means that when we receive the interrupt we can call

 * perf_event_do_pending() that handles all of the work with

 * interrupts disabled.

 */

static inline void

set_perf_event_pending(void)

{

}



/* ARM performance counters start from 1 (in the cp15 accesses) so use the

 * same indexes here for consistency. */

#define PERF_EVENT_INDEX_OFFSET 1

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