mm/damon: remove the target id concept

DAMON asks each monitoring target ('struct damon_target') to have one
'unsigned long' integer called 'id', which should be unique among the
targets of same monitoring context.  Meaning of it is, however, totally up
to the monitoring primitives that registered to the monitoring context.
For example, the virtual address spaces monitoring primitives treats the
id as a 'struct pid' pointer.

This makes the code flexible, but ugly, not well-documented, and
type-unsafe[1].  Also, identification of each target can be done via its
index.  For the reason, this commit removes the concept and uses clear
type definition.  For now, only 'struct pid' pointer is used for the
virtual address spaces monitoring.  If DAMON is extended in future so that
we need to put another identifier field in the struct, we will use a union
for such primitives-dependent fields and document which primitives are
using which type.

[1] https://lore.kernel.org/linux-mm/20211013154535.4aaeaaf9d0182922e405dd1e@linux-foundation.org/

Link: https://lkml.kernel.org/r/20211230100723.2238-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 22 insertions, 41 deletions

diff --git a/mm/damon/dbgfs-test.h b/mm/damon/dbgfs-test.h
index c1c988b607bc..0d3a14c00acf 100644
--- a/mm/damon/dbgfs-test.h
+++ b/mm/damon/dbgfs-test.h
@@ -12,66 +12,58 @@
 
 #include <kunit/test.h>
 
-static void damon_dbgfs_test_str_to_target_ids(struct kunit *test)
+static void damon_dbgfs_test_str_to_ints(struct kunit *test)
 {
 	char *question;
-	unsigned long *answers;
-	unsigned long expected[] = {12, 35, 46};
+	int *answers;
+	int expected[] = {12, 35, 46};
 	ssize_t nr_integers = 0, i;
 
 	question = "123";
-	answers = str_to_target_ids(question, strlen(question),
-			&nr_integers);
+	answers = str_to_ints(question, strlen(question), &nr_integers);
 	KUNIT_EXPECT_EQ(test, (ssize_t)1, nr_integers);
-	KUNIT_EXPECT_EQ(test, 123ul, answers[0]);
+	KUNIT_EXPECT_EQ(test, 123, answers[0]);
 	kfree(answers);
 
 	question = "123abc";
-	answers = str_to_target_ids(question, strlen(question),
-			&nr_integers);
+	answers = str_to_ints(question, strlen(question), &nr_integers);
 	KUNIT_EXPECT_EQ(test, (ssize_t)1, nr_integers);
-	KUNIT_EXPECT_EQ(test, 123ul, answers[0]);
+	KUNIT_EXPECT_EQ(test, 123, answers[0]);
 	kfree(answers);
 
 	question = "a123";
-	answers = str_to_target_ids(question, strlen(question),
-			&nr_integers);
+	answers = str_to_ints(question, strlen(question), &nr_integers);
 	KUNIT_EXPECT_EQ(test, (ssize_t)0, nr_integers);
 	kfree(answers);
 
 	question = "12 35";
-	answers = str_to_target_ids(question, strlen(question),
-			&nr_integers);
+	answers = str_to_ints(question, strlen(question), &nr_integers);
 	KUNIT_EXPECT_EQ(test, (ssize_t)2, nr_integers);
 	for (i = 0; i < nr_integers; i++)
 		KUNIT_EXPECT_EQ(test, expected[i], answers[i]);
 	kfree(answers);
 
 	question = "12 35 46";
-	answers = str_to_target_ids(question, strlen(question),
-			&nr_integers);
+	answers = str_to_ints(question, strlen(question), &nr_integers);
 	KUNIT_EXPECT_EQ(test, (ssize_t)3, nr_integers);
 	for (i = 0; i < nr_integers; i++)
 		KUNIT_EXPECT_EQ(test, expected[i], answers[i]);
 	kfree(answers);
 
 	question = "12 35 abc 46";
-	answers = str_to_target_ids(question, strlen(question),
-			&nr_integers);
+	answers = str_to_ints(question, strlen(question), &nr_integers);
 	KUNIT_EXPECT_EQ(test, (ssize_t)2, nr_integers);
 	for (i = 0; i < 2; i++)
 		KUNIT_EXPECT_EQ(test, expected[i], answers[i]);
 	kfree(answers);
 
 	question = "";
-	answers = str_to_target_ids(question, strlen(question),
-			&nr_integers);
+	answers = str_to_ints(question, strlen(question), &nr_integers);
 	KUNIT_EXPECT_EQ(test, (ssize_t)0, nr_integers);
 	kfree(answers);
 
 	question = "\n";
-	answers = str_to_target_ids(question, strlen(question),
-			&nr_integers);
+	answers = str_to_ints(question, strlen(question), &nr_integers);
 	KUNIT_EXPECT_EQ(test, (ssize_t)0, nr_integers);
 	kfree(answers);
 }
@@ -79,30 +71,20 @@ static void damon_dbgfs_test_str_to_target_ids(struct kunit *test)
 static void damon_dbgfs_test_set_targets(struct kunit *test)
 {
 	struct damon_ctx *ctx = dbgfs_new_ctx();
-	unsigned long ids[] = {1, 2, 3};
 	char buf[64];
 
-	/* Make DAMON consider target id as plain number */
-	ctx->primitive.target_valid = NULL;
-	ctx->primitive.cleanup = NULL;
+	/* Make DAMON consider target has no pid */
+	ctx->primitive = (struct damon_primitive){};
 
-	dbgfs_set_targets(ctx, ids, 3);
-	sprint_target_ids(ctx, buf, 64);
-	KUNIT_EXPECT_STREQ(test, (char *)buf, "1 2 3\n");
-
-	dbgfs_set_targets(ctx, NULL, 0);
+	dbgfs_set_targets(ctx, 0, NULL);
 	sprint_target_ids(ctx, buf, 64);
 	KUNIT_EXPECT_STREQ(test, (char *)buf, "\n");
 
-	dbgfs_set_targets(ctx, (unsigned long []){1, 2}, 2);
-	sprint_target_ids(ctx, buf, 64);
-	KUNIT_EXPECT_STREQ(test, (char *)buf, "1 2\n");
-
-	dbgfs_set_targets(ctx, (unsigned long []){2}, 1);
+	dbgfs_set_targets(ctx, 1, NULL);
 	sprint_target_ids(ctx, buf, 64);
-	KUNIT_EXPECT_STREQ(test, (char *)buf, "2\n");
+	KUNIT_EXPECT_STREQ(test, (char *)buf, "42\n");
 
-	dbgfs_set_targets(ctx, NULL, 0);
+	dbgfs_set_targets(ctx, 0, NULL);
 	sprint_target_ids(ctx, buf, 64);
 	KUNIT_EXPECT_STREQ(test, (char *)buf, "\n");
 
@@ -112,7 +94,6 @@ static void damon_dbgfs_test_set_targets(struct kunit *test)
 static void damon_dbgfs_test_set_init_regions(struct kunit *test)
 {
 	struct damon_ctx *ctx = damon_new_ctx();
-	unsigned long ids[] = {1, 2, 3};
 	/* Each line represents one region in ``<target idx> <start> <end>`` */
 	char * const valid_inputs[] = {"1 10 20\n 1   20 30\n1 35 45",
 		"1 10 20\n",
@@ -130,7 +111,7 @@ static void damon_dbgfs_test_set_init_regions(struct kunit *test)
 	int i, rc;
 	char buf[256];
 
-	dbgfs_set_targets(ctx, ids, 3);
+	dbgfs_set_targets(ctx, 3, NULL);
 
 	/* Put valid inputs and check the results */
 	for (i = 0; i < ARRAY_SIZE(valid_inputs); i++) {
@@ -158,12 +139,12 @@ static void damon_dbgfs_test_set_init_regions(struct kunit *test)
 		KUNIT_EXPECT_STREQ(test, (char *)buf, "");
 	}
 
-	dbgfs_set_targets(ctx, NULL, 0);
+	dbgfs_set_targets(ctx, 0, NULL);
 	damon_destroy_ctx(ctx);
 }
 
 static struct kunit_case damon_test_cases[] = {
-	KUNIT_CASE(damon_dbgfs_test_str_to_target_ids),
+	KUNIT_CASE(damon_dbgfs_test_str_to_ints),
 	KUNIT_CASE(damon_dbgfs_test_set_targets),
 	KUNIT_CASE(damon_dbgfs_test_set_init_regions),
 	{},