[PATCH 1/2] introduce new interface schedule_work_on

From: Zhang Rui
Date: Thu Jul 03 2008 - 08:22:42 EST


This interface allows adding a job on a specific cpu.

Although a work struct on a cpu will be scheduled to other cpu if the cpu dies,
there is a recursion if a work task tries to offline the cpu it's running on.
we need to schedule the task to a specific cpu in this case.
http://bugzilla.kernel.org/show_bug.cgi?id=10897

Signed-off-by: Zhang Rui <rui.zhang@xxxxxxxxx>
Tested-by: Rus <harbour@xxxxxxxxxxx>
---
include/linux/workqueue.h | 1 +
kernel/workqueue.c | 38 ++++++++++++++++++++++++++++++++++++++
2 files changed, 39 insertions(+)

Index: linux-2.6/include/linux/workqueue.h
===================================================================
--- linux-2.6.orig/include/linux/workqueue.h 2008-07-03 11:13:23.000000000 +0800
+++ linux-2.6/include/linux/workqueue.h 2008-07-03 11:13:25.000000000 +0800
@@ -188,6 +188,7 @@
extern void flush_scheduled_work(void);

extern int schedule_work(struct work_struct *work);
+extern int schedule_work_on(int cpu, struct work_struct *work);
extern int schedule_delayed_work(struct delayed_work *work, unsigned long delay);
extern int schedule_delayed_work_on(int cpu, struct delayed_work *work,
unsigned long delay);
Index: linux-2.6/kernel/workqueue.c
===================================================================
--- linux-2.6.orig/kernel/workqueue.c 2008-07-03 11:13:23.000000000 +0800
+++ linux-2.6/kernel/workqueue.c 2008-07-03 11:14:56.000000000 +0800
@@ -175,6 +175,31 @@
}
EXPORT_SYMBOL_GPL(queue_work);

+/**
+ * queue_work_on - queue work on specific cpu
+ * @cpu: CPU number to execute work on
+ * @wq: workqueue to use
+ * @work: work to queue
+ *
+ * Returns 0 if @work was already on a queue, non-zero otherwise.
+ *
+ * We queue the work to a specific CPU
+ */
+static int
+queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work)
+{
+ int ret = 0;
+
+ if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) {
+ BUG_ON(!list_empty(&work->entry));
+ preempt_disable();
+ __queue_work(wq_per_cpu(wq, cpu), work);
+ preempt_enable();
+ ret = 1;
+ }
+ return ret;
+}
+
static void delayed_work_timer_fn(unsigned long __data)
{
struct delayed_work *dwork = (struct delayed_work *)__data;
@@ -553,6 +578,19 @@
}
EXPORT_SYMBOL(schedule_work);

+/*
+ * schedule_work_on - put work task on a specific cpu
+ * @cpu: cpu to put the work task on
+ * @work: job to be done
+ *
+ * This puts a job on a specific cpu
+ */
+int schedule_work_on(int cpu, struct work_struct *work)
+{
+ return queue_work_on(cpu, keventd_wq, work);
+}
+EXPORT_SYMBOL(schedule_work_on);
+
/**
* schedule_delayed_work - put work task in global workqueue after delay
* @dwork: job to be done


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