[RFC PATCH v2 1/6] mm/damon: reintroduce damon_operations->cleanup()

[Akinobu Mita <akinobu.mita@gmail.com>]

Commit 50962b16c0d6 ("mm/damon: remove damon_operations->cleanup()")
removed damon_operations->cleanup(). However in order to support perf
event based access checks for physical and virtual address space
monitoring, damon_operations->cleanup() is required to release
perf events created by damon_operations->init().
---
 include/linux/damon.h | 3 +++
 mm/damon/core.c       | 2 ++
 mm/damon/paddr.c      | 1 +
 mm/damon/vaddr.c      | 1 +
 4 files changed, 7 insertions(+)

diff --git a/include/linux/damon.h b/include/linux/damon.h
index a4fea23da857..49d2983af4a8 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -607,6 +607,7 @@ enum damon_ops_id {
  * @apply_scheme:		Apply a DAMON-based operation scheme.
  * @target_valid:		Determine if the target is valid.
  * @cleanup_target:		Clean up each target before deallocation.
+ * @cleanup:			Clean up the context.
  *
  * DAMON can be extended for various address spaces and usages.  For this,
  * users should register the low level operations for their target address
@@ -639,6 +640,7 @@ enum damon_ops_id {
  * @target_valid should check whether the target is still valid for the
  * monitoring.
  * @cleanup_target is called before the target will be deallocated.
+ * @cleanup is called from @kdamond just before its termination.
  */
 struct damon_operations {
 	enum damon_ops_id id;
@@ -654,6 +656,7 @@ struct damon_operations {
 			struct damos *scheme, unsigned long *sz_filter_passed);
 	bool (*target_valid)(struct damon_target *t);
 	void (*cleanup_target)(struct damon_target *t);
+	void (*cleanup)(struct damon_ctx *context);
 };
 
 /*
diff --git a/mm/damon/core.c b/mm/damon/core.c
index adfc52fee9dc..d0d9659658bd 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -2841,6 +2841,8 @@ static int kdamond_fn(void *data)
 done:
 	damon_destroy_targets(ctx);
 
+	if (ctx->ops.cleanup)
+		ctx->ops.cleanup(ctx);
 	kfree(ctx->regions_score_histogram);
 	kdamond_call(ctx, true);
 	damos_walk_cancel(ctx);
diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index 9bfe48826840..4c2c935d82d6 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -373,6 +373,7 @@ static int __init damon_pa_initcall(void)
 		.prepare_access_checks = damon_pa_prepare_access_checks,
 		.check_accesses = damon_pa_check_accesses,
 		.target_valid = NULL,
+		.cleanup = NULL,
 		.apply_scheme = damon_pa_apply_scheme,
 		.get_scheme_score = damon_pa_scheme_score,
 	};
diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c
index 729b7ffd3565..8a58aa912112 100644
--- a/mm/damon/vaddr.c
+++ b/mm/damon/vaddr.c
@@ -1013,6 +1013,7 @@ static int __init damon_va_initcall(void)
 		.check_accesses = damon_va_check_accesses,
 		.target_valid = damon_va_target_valid,
 		.cleanup_target = damon_va_cleanup_target,
+		.cleanup = NULL,
 		.apply_scheme = damon_va_apply_scheme,
 		.get_scheme_score = damon_va_scheme_score,
 	};
-- 
2.43.0