workqueue: reimplement work flushing using linked works
A work is linked to the next one by having WORK_STRUCT_LINKED bit set
and these links can be chained. When a linked work is dispatched to a
worker, all linked works are dispatched to the worker's newly added
->scheduled queue and processed back-to-back.
Currently, as there's only single worker per cwq, having linked works
doesn't make any visible behavior difference. This change is to
prepare for multiple shared workers per cpu.
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 8762f62..4f4fdba 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -24,8 +24,9 @@
enum {
WORK_STRUCT_PENDING_BIT = 0, /* work item is pending execution */
+ WORK_STRUCT_LINKED_BIT = 1, /* next work is linked to this one */
#ifdef CONFIG_DEBUG_OBJECTS_WORK
- WORK_STRUCT_STATIC_BIT = 1, /* static initializer (debugobjects) */
+ WORK_STRUCT_STATIC_BIT = 2, /* static initializer (debugobjects) */
WORK_STRUCT_COLOR_SHIFT = 3, /* color for workqueue flushing */
#else
WORK_STRUCT_COLOR_SHIFT = 2, /* color for workqueue flushing */
@@ -34,6 +35,7 @@
WORK_STRUCT_COLOR_BITS = 4,
WORK_STRUCT_PENDING = 1 << WORK_STRUCT_PENDING_BIT,
+ WORK_STRUCT_LINKED = 1 << WORK_STRUCT_LINKED_BIT,
#ifdef CONFIG_DEBUG_OBJECTS_WORK
WORK_STRUCT_STATIC = 1 << WORK_STRUCT_STATIC_BIT,
#else