[RFC PATCH 02/27] mm/damon/core: implement data attribute report queue

[SJ Park <sj@kernel.org>]

Implement DAMON core internal data structure for queuing received
data attribute reports.  Initialize the queue for up to 1,000 reports,
inside the DAMON init routine.  Also update damon_initialized() to
return false for the setup failure of the queue.

Signed-off-by: SJ Park <sj@kernel.org>
---
 mm/damon/core.c | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/mm/damon/core.c b/mm/damon/core.c
index 0a056949604f9..3f87a7eec442e 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -2334,6 +2334,25 @@ int damos_walk(struct damon_ctx *ctx, struct damos_walk_control *control)
 	return 0;
 }
 
+/*
+ * struct damon_report_queue - &struct damon_report queue.
+ *
+ * @lock:	Represent if this queue is being used by someone.
+ * @head:	Head of the queue.
+ * @tail:	Tail of the queue.
+ * @size:	Size of the queue.
+ * @reports:	Array of &struct damon_report.
+ */
+struct damon_report_queue {
+	atomic_t lock;
+	unsigned int tail;
+	unsigned int size;
+	unsigned int nr_reports;
+	struct damon_report *reports;
+};
+
+struct damon_report_queue damon_report_queue;
+
 /*
  * Reset the aggregated monitoring results ('nr_accesses' of each region).
  */
@@ -4308,7 +4327,7 @@ void damon_update_region_access_rate(struct damon_region *r, bool accessed)
  */
 bool damon_initialized(void)
 {
-	return damon_region_cache != NULL;
+	return damon_region_cache && damon_report_queue.reports;
 }
 
 static int __init damon_init(void)
@@ -4319,6 +4338,14 @@ static int __init damon_init(void)
 		return -ENOMEM;
 	}
 
+	damon_report_queue.size = 1000;
+	damon_report_queue.reports = kmalloc_objs(*damon_report_queue.reports,
+			1000, GFP_KERNEL);
+	if (!damon_report_queue.reports) {
+		pr_err("report queue alloc fail\n");
+		return -ENOMEM;
+	}
+
 	return 0;
 }
 
-- 
2.47.3