workqueue: remove the stale comment in pwq_unbound_release_workfn()

In 75ccf5950f82 ("workqueue: prepare flush_workqueue() for dynamic
creation and destrucion of unbound pool_workqueues"), a comment
about the synchronization for the pwq in pwq_unbound_release_workfn()
was added. The comment claimed the flush_mutex wasn't strictly
necessary, it was correct in that time, due to the pwq was protected
by workqueue_lock.

But it is incorrect now since the wq->flush_mutex was renamed to
wq->mutex and workqueue_lock was removed, the wq->mutex is strictly
needed. But the comment was miss-updated when the synchronization
was changed.

This patch removes the incorrect comments and doesn't add any new
comment to explain why wq->mutex is needed here, which is definitely
obvious and wq->pwqs_node has "WQ" notation in its definition which is
better comment.

The old commit mentioned above also introduced a comment in link_pwq()
about the synchronization. This comment is also removed in this patch
since the whole link_pwq() is proteced by wq->mutex.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 4d9600f..0732d33 100644 (file)
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -3530,11 +3530,6 @@ static void pwq_unbound_release_workfn(struct work_struct *work)
        if (WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND)))
                return;
 
-       /*
-        * Unlink @pwq.  Synchronization against wq->mutex isn't strictly
-        * necessary on release but do it anyway.  It's easier to verify
-        * and consistent with the linking path.
-        */
        mutex_lock(&wq->mutex);
        list_del_rcu(&pwq->pwqs_node);
        is_last = list_empty(&wq->pwqs);
@@ -3631,10 +3626,7 @@ static void link_pwq(struct pool_workqueue *pwq)
        if (!list_empty(&pwq->pwqs_node))
                return;
 
-       /*
-        * Set the matching work_color.  This is synchronized with
-        * wq->mutex to avoid confusing flush_workqueue().
-        */
+       /* set the matching work_color */
        pwq->work_color = wq->work_color;
 
        /* sync max_active to the current setting */