[PATCH v2 1/1] rcuscale: add kfree_rcu() single-argument scale test

[Uladzislau Rezki (Sony)]

To stress and test a single argument of kfree_rcu() call, we
should to have a special coverage for it. We used to have it
in the test-suite related to vmalloc stressing. The reason is
the rcuscale is a correct place for RCU related things.

Therefore introduce two torture_param() variables, one is for
single-argument scale test and another one for double-argument
scale test.

By default kfree_rcu_test_single and kfree_rcu_test_double are
initialized to false. If both have the same value (false or true)
both are tested in one run, otherwise only the one with value
true is tested. The value of this is that it allows testing of
both options with one test.

Signed-off-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
---
 kernel/rcu/rcuscale.c | 33 ++++++++++++++++++++++++++++-----
 1 file changed, 28 insertions(+), 5 deletions(-)

diff --git a/kernel/rcu/rcuscale.c b/kernel/rcu/rcuscale.c
index 06491d5530db..0cde5c17f06c 100644
--- a/kernel/rcu/rcuscale.c
+++ b/kernel/rcu/rcuscale.c
@@ -625,6 +625,8 @@ rcu_scale_shutdown(void *arg)
 torture_param(int, kfree_nthreads, -1, "Number of threads running loops of kfree_rcu().");
 torture_param(int, kfree_alloc_num, 8000, "Number of allocations and frees done in an iteration.");
 torture_param(int, kfree_loops, 10, "Number of loops doing kfree_alloc_num allocations and frees.");
+torture_param(int, kfree_rcu_test_single, 0, "Do we run a kfree_rcu() single-argument scale test?");
+torture_param(int, kfree_rcu_test_double, 0, "Do we run a kfree_rcu() double-argument scale test?");
 
 static struct task_struct **kfree_reader_tasks;
 static int kfree_nrealthreads;
@@ -641,7 +643,7 @@ kfree_scale_thread(void *arg)
 {
 	int i, loop = 0;
 	long me = (long)arg;
-	struct kfree_obj *alloc_ptr;
+	struct kfree_obj *alloc_ptr[2];
 	u64 start_time, end_time;
 	long long mem_begin, mem_during = 0;
 
@@ -665,12 +667,33 @@ kfree_scale_thread(void *arg)
 			mem_during = (mem_during + si_mem_available()) / 2;
 		}
 
+		// By default kfree_rcu_test_single and kfree_rcu_test_double are
+		// initialized to false. If both have the same value (false or true)
+		// both are tested in one run, otherwise only the one with value
+		// true is tested.
 		for (i = 0; i < kfree_alloc_num; i++) {
-			alloc_ptr = kmalloc(kfree_mult * sizeof(struct kfree_obj), GFP_KERNEL);
-			if (!alloc_ptr)
-				return -ENOMEM;
+			alloc_ptr[0] = kmalloc(kfree_mult * sizeof(struct kfree_obj), GFP_KERNEL);
+			alloc_ptr[1] = (kfree_rcu_test_single == kfree_rcu_test_double) ?
+				kmalloc(kfree_mult * sizeof(struct kfree_obj), GFP_KERNEL) : NULL;
+
+			// 0 ptr. is freed either over single or double argument.
+			if (alloc_ptr[0]) {
+				if (kfree_rcu_test_single == kfree_rcu_test_double ||
+						kfree_rcu_test_single) {
+					kfree_rcu(alloc_ptr[0]);
+				} else {
+					kfree_rcu(alloc_ptr[0], rh);
+				}
+			}
+
+			// 1 ptr. is always freed over double argument.
+			if (alloc_ptr[1])
+				kfree_rcu(alloc_ptr[1], rh);
 
-			kfree_rcu(alloc_ptr, rh);
+			if (!alloc_ptr[0] ||
+					(kfree_rcu_test_single == kfree_rcu_test_double &&
+						!alloc_ptr[1]))
+				return -ENOMEM;
 		}
 
 		cond_resched();
-- 
2.20.1

--
Vlad Rezki