[RFC PATCH 2/8] mm/damon/core: do parameter testing commit on damon_start()

[SJ Park <sj@kernel.org>]

damon_start() and damon_commit_ctx() are two main DAMON core API
functions for setting whole DAMON parameters.  While damon_commit_ctx()
does holistic parameters testing, damon_start() just believes the caller
validated the whole thing.  Embed the holistic parameter check that is
already in damon_commit_ctx() into damon_start().  After this change,
the callers can safely call damon_start() without validating the
parameters.

Signed-off-by: SJ Park <sj@kernel.org>
---
 mm/damon/core.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/mm/damon/core.c b/mm/damon/core.c
index 62c27002219cd..6b30cb6007e54 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -1865,6 +1865,8 @@ static int __damon_start(struct damon_ctx *ctx)
 	return err;
 }
 
+static int __damon_commit_ctx(struct damon_ctx *dst, struct damon_ctx *src);
+
 /**
  * damon_start() - Starts the monitorings for a given group of contexts.
  * @ctxs:	an array of the pointers for contexts to start monitoring
@@ -1882,13 +1884,22 @@ static int __damon_start(struct damon_ctx *ctx)
  */
 int damon_start(struct damon_ctx **ctxs, int nr_ctxs, bool exclusive)
 {
+	struct damon_ctx *test_ctx;
 	int i;
 	int err = 0;
 
+	test_ctx = damon_new_ctx();
+	if (!test_ctx)
+		return -ENOMEM;
+
 	for (i = 0; i < nr_ctxs; i++) {
-		if (!is_power_of_2(ctxs[i]->min_region_sz))
-			return -EINVAL;
+		err = __damon_commit_ctx(test_ctx, ctxs[i]);
+		if (err) {
+			damon_destroy_ctx(test_ctx);
+			return err;
+		}
 	}
+	damon_destroy_ctx(test_ctx);
 
 	mutex_lock(&damon_lock);
 	if ((exclusive && nr_running_ctxs) ||
-- 
2.47.3