mm/damon: remove return value from before_terminate callback

Since the return value of 'before_terminate' callback is never used, we
make it have no return value.

Link: https://lkml.kernel.org/r/20211029005023.8895-1-changbin.du@gmail.com
Signed-off-by: Changbin Du <changbin.du@gmail.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/damon.h

@@ -322,7 +322,7 @@ struct damon_callback {
 	int (*before_start)(struct damon_ctx *context);
 	int (*after_sampling)(struct damon_ctx *context);
 	int (*after_aggregation)(struct damon_ctx *context);
-	int (*before_terminate)(struct damon_ctx *context);
+	void (*before_terminate)(struct damon_ctx *context);
 };
 
 /**

mm/damon/dbgfs.c

@@ -645,18 +645,17 @@ static void dbgfs_fill_ctx_dir(struct dentry *dir, struct damon_ctx *ctx)
 		debugfs_create_file(file_names[i], 0600, dir, ctx, fops[i]);
 }
 
-static int dbgfs_before_terminate(struct damon_ctx *ctx)
+static void dbgfs_before_terminate(struct damon_ctx *ctx)
 {
 	struct damon_target *t, *next;
 
 	if (!targetid_is_pid(ctx))
-		return 0;
+		return;
 
 	damon_for_each_target_safe(t, next, ctx) {
 		put_pid((struct pid *)t->id);
 		damon_destroy_target(t);
 	}
-	return 0;
 }
 
 static struct damon_ctx *dbgfs_new_ctx(void)