softirq: Add support for triggering softirq work on softirqs.

This is basically a genericization of Jens Axboe's block layer
remote softirq changes.

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 54b3623434e..35a61dc60d5 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -11,6 +11,8 @@
 #include <linux/hardirq.h>
 #include <linux/sched.h>
 #include <linux/irqflags.h>
+#include <linux/smp.h>
+#include <linux/percpu.h>
 #include <asm/atomic.h>
 #include <asm/ptrace.h>
 #include <asm/system.h>
@@ -273,6 +275,25 @@ extern void softirq_init(void);
 extern void raise_softirq_irqoff(unsigned int nr);
 extern void raise_softirq(unsigned int nr);
 
+/* This is the worklist that queues up per-cpu softirq work.
+ *
+ * send_remote_sendirq() adds work to these lists, and
+ * the softirq handler itself dequeues from them.  The queues
+ * are protected by disabling local cpu interrupts and they must
+ * only be accessed by the local cpu that they are for.
+ */
+DECLARE_PER_CPU(struct list_head [NR_SOFTIRQS], softirq_work_list);
+
+/* Try to send a softirq to a remote cpu.  If this cannot be done, the
+ * work will be queued to the local cpu.
+ */
+extern void send_remote_softirq(struct call_single_data *cp, int cpu, int softirq);
+
+/* Like send_remote_softirq(), but the caller must disable local cpu interrupts
+ * and compute the current cpu, passed in as 'this_cpu'.
+ */
+extern void __send_remote_softirq(struct call_single_data *cp, int cpu,
+                                  int this_cpu, int softirq);
 
 /* Tasklets --- multithreaded analogue of BHs.