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: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Kyle McMartin <kyle@mcmartin.ca>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
[ various fixes ]
Signed-off-by: Huang Ying <ying.huang@intel.com>
LKML-Reference: <1287036094.7768.291.camel@yhuang-dev>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/alpha/kernel/time.c b/arch/alpha/kernel/time.c
index 396af17..0f1d849 100644
--- a/arch/alpha/kernel/time.c
+++ b/arch/alpha/kernel/time.c
@@ -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 @@
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 @@
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