[v3,17/17] bcache: add the missing comments for smp_mb()/smp_wmb()

Commit Message

Coly Li Aug. 11, 2018, 5:20 a.m. UTC

Checkpatch.pl warns there are 2 locations of smp_mb() and smp_wmb()
without code comment. This patch adds the missing code comments for
these memory barrier calls.

Signed-off-by: Coly Li <[e-mail]>
Reviewed-by: Shenghui Wang <[e-mail]>
---
 drivers/md/bcache/closure.h | 4 +++-
 drivers/md/bcache/super.c   | 2 +-
 2 files changed, 4 insertions(+), 2 deletions(-)

Patch

diff --git a/drivers/md/bcache/closure.h b/drivers/md/bcache/closure.h
index 7f3594c0be14..eca0d496b686 100644
--- a/drivers/md/bcache/closure.h
+++ b/drivers/md/bcache/closure.h
@@ -289,10 +289,12 @@  static inline void closure_init_stack(struct closure *cl)
 }
 
 /**
- * closure_wake_up - wake up all closures on a wait list.
+ * closure_wake_up - wake up all closures on a wait list,
+ *		     with memory barrier
  */
 static inline void closure_wake_up(struct closure_waitlist *list)
 {
+	/* Memory barrier for the wait list */
 	smp_mb();
 	__closure_wake_up(list);
 }
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index e637d74e2908..94c756c66bd7 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1136,11 +1136,11 @@  int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c,
 	list_move(&dc->list, &c->cached_devs);
 	calc_cached_dev_sectors(c);
 
-	smp_wmb();
 	/*
 	 * dc->c must be set before dc->count != 0 - paired with the mb in
 	 * cached_dev_get()
 	 */
+	smp_wmb();
 	refcount_set(&dc->count, 1);
 
 	/* Block writeback thread, but spawn it */