2 files changed, 21 insertions, 29 deletions

diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index d74a529ed13..5f76001c4e6 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -25,17 +25,19 @@ typedef void (*work_func_t)(struct work_struct *work);
 
 enum {
         WORK_STRUCT_PENDING_BIT = 0,    /* work item is pending execution */
-        WORK_STRUCT_LINKED_BIT  = 1,    /* next work is linked to this one */
+        WORK_STRUCT_CWQ_BIT     = 1,    /* data points to cwq */
+        WORK_STRUCT_LINKED_BIT  = 2,    /* next work is linked to this one */
 #ifdef CONFIG_DEBUG_OBJECTS_WORK
-        WORK_STRUCT_STATIC_BIT  = 2,    /* static initializer (debugobjects) */
-        WORK_STRUCT_COLOR_SHIFT = 3,    /* color for workqueue flushing */
+        WORK_STRUCT_STATIC_BIT  = 3,    /* static initializer (debugobjects) */
+        WORK_STRUCT_COLOR_SHIFT = 4,    /* color for workqueue flushing */
 #else
-        WORK_STRUCT_COLOR_SHIFT = 2,    /* color for workqueue flushing */
+        WORK_STRUCT_COLOR_SHIFT = 3,    /* color for workqueue flushing */
 #endif
 
         WORK_STRUCT_COLOR_BITS  = 4,
 
         WORK_STRUCT_PENDING     = 1 << WORK_STRUCT_PENDING_BIT,
+        WORK_STRUCT_CWQ         = 1 << WORK_STRUCT_CWQ_BIT,
         WORK_STRUCT_LINKED      = 1 << WORK_STRUCT_LINKED_BIT,
 #ifdef CONFIG_DEBUG_OBJECTS_WORK
         WORK_STRUCT_STATIC      = 1 << WORK_STRUCT_STATIC_BIT,
@@ -56,8 +58,8 @@ enum {
         WORK_CPU_LAST           = WORK_CPU_NONE,
 
         /*
-         * Reserve 6 bits off of cwq pointer w/ debugobjects turned
-         * off.  This makes cwqs aligned to 64 bytes which isn't too
+         * Reserve 7 bits off of cwq pointer w/ debugobjects turned
+         * off.  This makes cwqs aligned to 128 bytes which isn't too
          * excessive while allowing 15 workqueue flush colors.
          */
         WORK_STRUCT_FLAG_BITS   = WORK_STRUCT_COLOR_SHIFT +
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index c11edc9c936..e5cb7faac58 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -468,10 +468,9 @@ static int work_next_color(int color)
 }
 
 /*
- * Work data points to the cwq while a work is on queue.  Once
- * execution starts, it points to the cpu the work was last on.  This
- * can be distinguished by comparing the data value against
- * PAGE_OFFSET.
+ * A work's data points to the cwq with WORK_STRUCT_CWQ set while the
+ * work is on queue.  Once execution starts, WORK_STRUCT_CWQ is
+ * cleared and the work data contains the cpu number it was last on.
  *
  * set_work_{cwq|cpu}() and clear_work_data() can be used to set the
  * cwq, cpu or clear work->data.  These functions should only be
@@ -494,7 +493,7 @@ static void set_work_cwq(struct work_struct *work,
                          unsigned long extra_flags)
 {
         set_work_data(work, (unsigned long)cwq,
-                      WORK_STRUCT_PENDING | extra_flags);
+                      WORK_STRUCT_PENDING | WORK_STRUCT_CWQ | extra_flags);
 }
 
 static void set_work_cpu(struct work_struct *work, unsigned int cpu)
@@ -507,25 +506,24 @@ static void clear_work_data(struct work_struct *work)
         set_work_data(work, WORK_STRUCT_NO_CPU, 0);
 }
 
-static inline unsigned long get_work_data(struct work_struct *work)
-{
-        return atomic_long_read(&work->data) & WORK_STRUCT_WQ_DATA_MASK;
-}
-
 static struct cpu_workqueue_struct *get_work_cwq(struct work_struct *work)
 {
-        unsigned long data = get_work_data(work);
+        unsigned long data = atomic_long_read(&work->data);
 
-        return data >= PAGE_OFFSET ? (void *)data : NULL;
+        if (data & WORK_STRUCT_CWQ)
+                return (void *)(data & WORK_STRUCT_WQ_DATA_MASK);
+        else
+                return NULL;
 }
 
 static struct global_cwq *get_work_gcwq(struct work_struct *work)
 {
-        unsigned long data = get_work_data(work);
+        unsigned long data = atomic_long_read(&work->data);
         unsigned int cpu;
 
-        if (data >= PAGE_OFFSET)
-                return ((struct cpu_workqueue_struct *)data)->gcwq;
+        if (data & WORK_STRUCT_CWQ)
+                return ((struct cpu_workqueue_struct *)
+                        (data & WORK_STRUCT_WQ_DATA_MASK))->gcwq;
 
         cpu = data >> WORK_STRUCT_FLAG_BITS;
         if (cpu == WORK_CPU_NONE)
@@ -3501,14 +3499,6 @@ void __init init_workqueues(void)
         unsigned int cpu;
         int i;
 
-        /*
-         * The pointer part of work->data is either pointing to the
-         * cwq or contains the cpu number the work ran last on.  Make
-         * sure cpu number won't overflow into kernel pointer area so
-         * that they can be distinguished.
-         */
-        BUILD_BUG_ON(WORK_CPU_LAST << WORK_STRUCT_FLAG_BITS >= PAGE_OFFSET);
-
         hotcpu_notifier(workqueue_cpu_callback, CPU_PRI_WORKQUEUE);
 
         /* initialize gcwqs */