[PATCH] mm/damon/core: support multiple damon_call_control requests

[Enze Li <lienze@kylinos.cn>]

The current implementation only supports repeated calls to a single
damon_call_control request per context.  This limitation introduces
inefficiencies for scenarios that require registering multiple deferred
operations.

This patch modifies the implementation of kdamond_call() to support
repeated calls to multiple damon_call_control requests.  To demonstrate
the effect of this change, I made minor modifications to
samples/damon/prcl.c by adding a new request alongside the original
damon_call_control request and performed comparative tests.

Before applying the patch, I observed,

[  381.661821] damon_sample_prcl: start
[  381.668199] damon_sample_prcl: repeat_call_v2
[  381.668208] damon_sample_prcl: repeat_call
[  381.668211] damon_sample_prcl: wss: 0
[  381.675194] damon_sample_prcl: repeat_call
[  381.675202] damon_sample_prcl: wss: 0

after applying the patch, I saw,

[   61.750723] damon_sample_prcl: start
[   61.757104] damon_sample_prcl: repeat_call_v2
[   61.757106] damon_sample_prcl: repeat_call
[   61.757107] damon_sample_prcl: wss: 0
[   61.763067] damon_sample_prcl: repeat_call_v2
[   61.763069] damon_sample_prcl: repeat_call
[   61.763070] damon_sample_prcl: wss: 0

Signed-off-by: Enze Li <lienze@kylinos.cn>
---
 mm/damon/core.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/mm/damon/core.c b/mm/damon/core.c
index 109b050c795a..66b5bae44f22 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -2526,13 +2526,19 @@ static void kdamond_call(struct damon_ctx *ctx, bool cancel)
 			list_add(&control->list, &repeat_controls);
 		}
 	}
-	control = list_first_entry_or_null(&repeat_controls,
-			struct damon_call_control, list);
-	if (!control || cancel)
-		return;
-	mutex_lock(&ctx->call_controls_lock);
-	list_add_tail(&control->list, &ctx->call_controls);
-	mutex_unlock(&ctx->call_controls_lock);
+	while (true) {
+		control = list_first_entry_or_null(&repeat_controls,
+				struct damon_call_control, list);
+		if (!control)
+			break;
+		/* Unlink from the repeate_controls list. */
+		list_del(&control->list);
+		if (cancel)
+			continue;
+		mutex_lock(&ctx->call_controls_lock);
+		list_add(&control->list, &ctx->call_controls);
+		mutex_unlock(&ctx->call_controls_lock);
+	}
 }
 
 /* Returns negative error code if it's not activated but should return */

base-commit: 7d0a66e4bb9081d75c82ec4957c50034cb0ea449
-- 
2.52.0