[RFC PATCH 09/11] mm/damon/core: stop ctx in damon_call() before reruning an error

[SJ Park <sj@kernel.org>]

damon_call() failure makes the DAMON context to stop if it was running.
The stop is asynchronously done in kdamond thread, though.  The caller's
error handling should handle the race, too.  It is complicated and easy
to make mistakes.

Update damon_call() to ensure the context is stopped in the case.

Signed-off-by: SJ Park <sj@kernel.org>
---
 mm/damon/core.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/mm/damon/core.c b/mm/damon/core.c
index 1a6c30ae91711..5f16d2e13ebf7 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -2009,6 +2009,8 @@ int damon_kdamond_pid(struct damon_ctx *ctx)
  * @ctx has succeeded.  Otherwise, this function could fall into an indefinite
  * wait.
  *
+ * When this function is failed, the @ctx is guaranteed to be stopped.
+ *
  * Return: 0 on success, negative error code otherwise.
  */
 int damon_call(struct damon_ctx *ctx, struct damon_call_control *control)
@@ -2021,7 +2023,7 @@ int damon_call(struct damon_ctx *ctx, struct damon_call_control *control)
 	mutex_lock(&ctx->call_controls_lock);
 	if (ctx->call_controls_obsolete) {
 		mutex_unlock(&ctx->call_controls_lock);
-		return -ECANCELED;
+		goto canceled;
 	}
 	list_add_tail(&control->list, &ctx->call_controls);
 	mutex_unlock(&ctx->call_controls_lock);
@@ -2029,8 +2031,13 @@ int damon_call(struct damon_ctx *ctx, struct damon_call_control *control)
 		return 0;
 	wait_for_completion(&control->completion);
 	if (control->canceled)
-		return -ECANCELED;
+		goto canceled;
 	return 0;
+
+canceled:
+	__damon_stop(ctx);
+	return -ECANCELED;
+
 }
 
 /**
-- 
2.47.3