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-rw-r--r--Documentation/core-api/workqueue.rst21
1 files changed, 17 insertions, 4 deletions
diff --git a/Documentation/core-api/workqueue.rst b/Documentation/core-api/workqueue.rst
index 541d31de8926..3b22ed137662 100644
--- a/Documentation/core-api/workqueue.rst
+++ b/Documentation/core-api/workqueue.rst
@@ -216,10 +216,6 @@ resources, scheduled and executed.
This flag is meaningless for unbound wq.
-Note that the flag ``WQ_NON_REENTRANT`` no longer exists as all
-workqueues are now non-reentrant - any work item is guaranteed to be
-executed by at most one worker system-wide at any given time.
-
``max_active``
--------------
@@ -391,6 +387,23 @@ the stack trace of the offending worker thread. ::
The work item's function should be trivially visible in the stack
trace.
+Non-reentrance Conditions
+=========================
+
+Workqueue guarantees that a work item cannot be re-entrant if the following
+conditions hold after a work item gets queued:
+
+ 1. The work function hasn't been changed.
+ 2. No one queues the work item to another workqueue.
+ 3. The work item hasn't been reinitiated.
+
+In other words, if the above conditions hold, the work item is guaranteed to be
+executed by at most one worker system-wide at any given time.
+
+Note that requeuing the work item (to the same queue) in the self function
+doesn't break these conditions, so it's safe to do. Otherwise, caution is
+required when breaking the conditions inside a work function.
+
Kernel Inline Documentations Reference
======================================