[lttng-dev] [PATCH urcu 1/4] Fix: mixup between URCU_WORKQUEUE_RT and URCU_CALL_RCU_RT

Jérémie Galarneau jeremie.galarneau at efficios.com
Fri Dec 7 17:06:36 EST 2018

The work queue implementation is derived from the call-rcu thread. A
number of references seem to have been left in place when adapting the
code for its new purpose.

The URCU_CALL_RCU_RT flag is used by wake_worker_thread() while the
rest of the workqueue.c code uses URCU_WORKQUEUE_RT to determine if
the work queue was configured in real-time mode. Both flags are defined
to the same value (0x1) and the current internal user of the
work queue (lfht) never specifies any flags.

In practice, this does not cause any problem so I doubt this patch
needs to be backported. Feel free to rename "Fix" to "Clean-up".

There are a number of comments referencing call-rcu which may need
to be adapted. Changing them is left as an exercise to the maintainer
as I don't know if they apply to the workqueue thread.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau at efficios.com>
 src/workqueue.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/workqueue.c b/src/workqueue.c
index 17ea835..8561a7a 100644
--- a/src/workqueue.c
+++ b/src/workqueue.c
@@ -309,7 +309,7 @@ struct urcu_workqueue *urcu_workqueue_create(unsigned long flags,
 static void wake_worker_thread(struct urcu_workqueue *workqueue)
-	if (!(_CMM_LOAD_SHARED(workqueue->flags) & URCU_CALL_RCU_RT))
+	if (!(_CMM_LOAD_SHARED(workqueue->flags) & URCU_WORKQUEUE_RT))

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