workqueue: Remove now redundant lock acquisitions wrt. workqueue flushes

The workqueue code added manual lock acquisition annotations to catch
deadlocks.

After lockdepcrossrelease was introduced, some of those became redundant,
since wait_for_completion() already does the acquisition and tracking.

Remove the duplicate annotations.

Signed-off-by: Byungchul Park <byungchul.park@lge.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: amir73il@gmail.com
Cc: axboe@kernel.dk
Cc: darrick.wong@oracle.com
Cc: david@fromorbit.com
Cc: hch@infradead.org
Cc: idryomov@gmail.com
Cc: johan@kernel.org
Cc: johannes.berg@intel.com
Cc: kernel-team@lge.com
Cc: linux-block@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: linux-xfs@vger.kernel.org
Cc: oleg@redhat.com
Cc: tj@kernel.org
Link: http://lkml.kernel.org/r/1508921765-15396-9-git-send-email-byungchul.park@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 5 insertions, 18 deletions

diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 1c49431f3121..c8a572cb49be 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -218,7 +218,7 @@ static inline unsigned int work_static(struct work_struct *work) { return 0; }
                                                                         \
                 __init_work((_work), _onstack);                         \
                 (_work)->data = (atomic_long_t) WORK_DATA_INIT();       \
-                lockdep_init_map(&(_work)->lockdep_map, #_work, &__key, 0); \
+                lockdep_init_map(&(_work)->lockdep_map, "(work_completion)"#_work, &__key, 0); \
                 INIT_LIST_HEAD(&(_work)->entry);                        \
                 (_work)->func = (_func);                                \
         } while (0)
@@ -398,7 +398,7 @@ __alloc_workqueue_key(const char *fmt, unsigned int flags, int max_active,
         static struct lock_class_key __key;                             \
         const char *__lock_name;                                        \
                                                                         \
-        __lock_name = #fmt#args;                                        \
+        __lock_name = "(wq_completion)"#fmt#args;                       \
                                                                         \
         __alloc_workqueue_key((fmt), (flags), (max_active),             \
                               &__key, __lock_name, ##args);             \
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 39831b2f3c5f..160fdc6e839a 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -2497,15 +2497,8 @@ static void insert_wq_barrier(struct pool_workqueue *pwq,
         INIT_WORK_ONSTACK(&barr->work, wq_barrier_func);
         __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work));
 
-        /*
-         * Explicitly init the crosslock for wq_barrier::done, make its lock
-         * key a subkey of the corresponding work. As a result we won't
-         * build a dependency between wq_barrier::done and unrelated work.
-         */
-        lockdep_init_map_crosslock((struct lockdep_map *)&barr->done.map,
-                                   "(complete)wq_barr::done",
-                                   target->lockdep_map.key, 1);
-        __init_completion(&barr->done);
+        init_completion_map(&barr->done, &target->lockdep_map);
+
         barr->task = current;
 
         /*
@@ -2611,16 +2604,13 @@ void flush_workqueue(struct workqueue_struct *wq)
         struct wq_flusher this_flusher = {
                 .list = LIST_HEAD_INIT(this_flusher.list),
                 .flush_color = -1,
-                .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done),
+                .done = COMPLETION_INITIALIZER_ONSTACK_MAP(this_flusher.done, wq->lockdep_map),
         };
         int next_color;
 
         if (WARN_ON(!wq_online))
                 return;
 
-        lock_map_acquire(&wq->lockdep_map);
-        lock_map_release(&wq->lockdep_map);
-
         mutex_lock(&wq->mutex);
 
         /*
@@ -2883,9 +2873,6 @@ bool flush_work(struct work_struct *work)
         if (WARN_ON(!wq_online))
                 return false;
 
-        lock_map_acquire(&work->lockdep_map);
-        lock_map_release(&work->lockdep_map);
-
         if (start_flush_work(work, &barr)) {
                 wait_for_completion(&barr.done);
                 destroy_work_on_stack(&barr.work);