Merge branch 'for-5.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

Pull workqueue fixes from Tejun Heo:
 "Workqueue has been incorrectly round-robining per-cpu work items.
  Hillf's patch fixes that.

  The other patch documents memory-ordering properties of workqueue
  operations"

* 'for-5.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: don't use wq_select_unbound_cpu() for bound works
  workqueue: Document (some) memory-ordering properties of {queue,schedule}_work()

1 files changed, 16 insertions, 0 deletions

diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 4261d1c6e87b..e48554e6526c 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -487,6 +487,19 @@ extern void wq_worker_comm(char *buf, size_t size, struct task_struct *task);
  *
  * We queue the work to the CPU on which it was submitted, but if the CPU dies
  * it can be processed by another CPU.
+ *
+ * Memory-ordering properties:  If it returns %true, guarantees that all stores
+ * preceding the call to queue_work() in the program order will be visible from
+ * the CPU which will execute @work by the time such work executes, e.g.,
+ *
+ * { x is initially 0 }
+ *
+ *   CPU0				CPU1
+ *
+ *   WRITE_ONCE(x, 1);			[ @work is being executed ]
+ *   r0 = queue_work(wq, work);		  r1 = READ_ONCE(x);
+ *
+ * Forbids: r0 == true && r1 == 0
  */
 static inline bool queue_work(struct workqueue_struct *wq,
 			      struct work_struct *work)
@@ -546,6 +559,9 @@ static inline bool schedule_work_on(int cpu, struct work_struct *work)
  * This puts a job in the kernel-global workqueue if it was not already
  * queued and leaves it in the same position on the kernel-global
  * workqueue otherwise.
+ *
+ * Shares the same memory-ordering properties of queue_work(), cf. the
+ * DocBook header of queue_work().
  */
 static inline bool schedule_work(struct work_struct *work)
 {