bcache: add the missing comments for smp_mb()/smp_wmb()

Coly Li · axboe · commit eb2b3d034511 · 2018-08-11T15:46:42.000-06:00
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 &lt;colyli@suse.de&gt;
Reviewed-by: Shenghui Wang &lt;shhuiw@foxmail.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
diff --git 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
@@ -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 */

Original file line number	Diff line number	Diff line change
`@@ -289,10 +289,12 @@ static inline void closure_init_stack(struct closure *cl)`
`289`	`289`	`}`
`290`	`290`
`291`	`291`	`/**`
`292`		`- * closure_wake_up - wake up all closures on a wait list.`
	`292`	`+ * closure_wake_up - wake up all closures on a wait list,`
	`293`	`+ * with memory barrier`
`293`	`294`	`*/`
`294`	`295`	`static inline void closure_wake_up(struct closure_waitlist *list)`
`295`	`296`	`{`
	`297`	`+ /* Memory barrier for the wait list */`
`296`	`298`	`smp_mb();`
`297`	`299`	`__closure_wake_up(list);`
`298`	`300`	`}`