SLOW_WORK: Wait for outstanding work items belonging to a module to clear

Wait for outstanding slow work items belonging to a module to clear when
unregistering that module as a user of the facility.  This prevents the put_ref
code of a work item from being taken away before it returns.

Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 10 insertions, 3 deletions

diff --git a/Documentation/slow-work.txt b/Documentation/slow-work.txt
index ebc50f808ea4..f12fda31dcdc 100644
--- a/Documentation/slow-work.txt
+++ b/Documentation/slow-work.txt
@@ -64,9 +64,11 @@ USING SLOW WORK ITEMS
 Firstly, a module or subsystem wanting to make use of slow work items must
 register its interest:
 
-         int ret = slow_work_register_user();
+         int ret = slow_work_register_user(struct module *module);
 
-This will return 0 if successful, or a -ve error upon failure.
+This will return 0 if successful, or a -ve error upon failure.  The module
+pointer should be the module interested in using this facility (almost
+certainly THIS_MODULE).
 
 
 Slow work items may then be set up by:
@@ -110,7 +112,12 @@ operation.  When all a module's slow work items have been processed, and the
 module has no further interest in the facility, it should unregister its
 interest:
 
-        slow_work_unregister_user();
+        slow_work_unregister_user(struct module *module);
+
+The module pointer is used to wait for all outstanding work items for that
+module before completing the unregistration.  This prevents the put_ref() code
+from being taken away before it completes.  module should almost certainly be
+THIS_MODULE.
 
 
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