workqueue: add and use WQ_MEM_RECLAIM flag

Add WQ_MEM_RECLAIM flag which currently maps to WQ_RESCUER, mark
WQ_RESCUER as internal and replace all external WQ_RESCUER usages to
WQ_MEM_RECLAIM.

This makes the API users express the intent of the workqueue instead
of indicating the internal mechanism used to guarantee forward
progress.  This is also to make it cleaner to add more semantics to
WQ_MEM_RECLAIM.  For example, if deemed necessary, memory reclaim
workqueues can be made highpri.

This patch doesn't introduce any functional change.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jeff Garzik <jgarzik@pobox.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 6 insertions, 5 deletions

diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index e33ff4a91703..03bbe903e5ce 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -243,11 +243,12 @@ enum {
         WQ_NON_REENTRANT        = 1 << 0, /* guarantee non-reentrance */
         WQ_UNBOUND              = 1 << 1, /* not bound to any cpu */
         WQ_FREEZEABLE           = 1 << 2, /* freeze during suspend */
-        WQ_RESCUER              = 1 << 3, /* has an rescue worker */
+        WQ_MEM_RECLAIM          = 1 << 3, /* may be used for memory reclaim */
         WQ_HIGHPRI              = 1 << 4, /* high priority */
         WQ_CPU_INTENSIVE        = 1 << 5, /* cpu instensive workqueue */
 
         WQ_DYING                = 1 << 6, /* internal: workqueue is dying */
+        WQ_RESCUER              = 1 << 7, /* internal: workqueue has rescuer */
 
         WQ_MAX_ACTIVE           = 512,    /* I like 512, better ideas? */
         WQ_MAX_UNBOUND_PER_CPU  = 4,      /* 4 * #cpus for unbound wq */
@@ -309,7 +310,7 @@ __alloc_workqueue_key(const char *name, unsigned int flags, int max_active,
 /**
  * alloc_ordered_workqueue - allocate an ordered workqueue
  * @name: name of the workqueue
- * @flags: WQ_* flags (only WQ_FREEZEABLE and WQ_RESCUER are meaningful)
+ * @flags: WQ_* flags (only WQ_FREEZEABLE and WQ_MEM_RECLAIM are meaningful)
  *
  * Allocate an ordered workqueue.  An ordered workqueue executes at
  * most one work item at any given time in the queued order.  They are
@@ -325,11 +326,11 @@ alloc_ordered_workqueue(const char *name, unsigned int flags)
 }
 
 #define create_workqueue(name)                                  \
-        alloc_workqueue((name), WQ_RESCUER, 1)
+        alloc_workqueue((name), WQ_MEM_RECLAIM, 1)
 #define create_freezeable_workqueue(name)                       \
-        alloc_workqueue((name), WQ_FREEZEABLE | WQ_UNBOUND | WQ_RESCUER, 1)
+        alloc_workqueue((name), WQ_FREEZEABLE | WQ_UNBOUND | WQ_MEM_RECLAIM, 1)
 #define create_singlethread_workqueue(name)                     \
-        alloc_workqueue((name), WQ_UNBOUND | WQ_RESCUER, 1)
+        alloc_workqueue((name), WQ_UNBOUND | WQ_MEM_RECLAIM, 1)
 
 extern void destroy_workqueue(struct workqueue_struct *wq);