test/mempool: bug demonstration test

This test demonstrates a serious bugs that exist in the mem-pool code
as ovf Zephyr v1.14.0, and probably earlier versions too. This bug is
fixed with PR #16966.

Signed-off-by: Nicolas Pitre <npitre@baylibre.com>

Author: Nicolas Pitre

tests/kernel/mem_pool/mem_pool_concept/src/main.c

@@ -9,6 +9,7 @@ extern void test_mpool_alloc_wait_prio(void);
 extern void test_mpool_alloc_size_roundup(void);
 extern void test_mpool_alloc_merge_failed_diff_size(void);
 extern void test_mpool_alloc_merge_failed_diff_parent(void);
+extern void test_mempool_spook(void);
 
 /*test case main entry*/
 void test_main(void)
@@ -17,7 +18,8 @@ void test_main(void)
 		ztest_unit_test(test_mpool_alloc_wait_prio),
 		ztest_unit_test(test_mpool_alloc_size_roundup),
 		ztest_unit_test(test_mpool_alloc_merge_failed_diff_size),
-		ztest_unit_test(test_mpool_alloc_merge_failed_diff_parent));
+		ztest_unit_test(test_mpool_alloc_merge_failed_diff_parent),
+		ztest_unit_test(test_mempool_spook));
 	ztest_run_test_suite(mpool_concept);
 }
 

tests/kernel/mem_pool/mem_pool_concept/src/test_mpool_spook.c

@@ -0,0 +1,88 @@
+/*
+ * Copyright (c) 2019 BayLibre SAS
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/*
+ * This test demonstrates a serious bugs that exist in the mem-pool code
+ * when the fix from PR #16966 is not applied.
+ *
+ * Expected output with the bug present:
+ *
+ *	allocating boxes
+ *	init box 3
+ *	show box 3: tic="tic" tac="tac" toe="toe"
+ *	init box 4
+ *	show box 4: tic="tic" tac="tac" toe="toe"
+ *	show box 3: tic="tic" tac="tac" toe="tic"
+ *	init box 3
+ *	show box 3: tic="tic" tac="tac" toe="toe"
+ *	show box 4: tic="toe" tac="tac" toe="toe"
+ */
+
+/**
+ * @brief Memory Pool Bug Tests
+ * @defgroup kernel_memory_pool_tests Memory Pool
+ * @ingroup all_tests
+ * @{
+ * @}
+ */
+
+#include <ztest.h>
+#include <zephyr.h>
+#include <misc/printk.h>
+
+K_MEM_POOL_DEFINE(my_pool, 8, 44, 9, 4);
+
+struct tic_tac_toe { char *tic; char *tac; char *toe; };
+
+static struct tic_tac_toe *boxes[9];
+
+static bool spooked;
+
+static void init_box(int n)
+{
+	printk("init box %d\n", n);
+	boxes[n]->tic = "tic";
+	boxes[n]->tac = "tac";
+	boxes[n]->toe = "toe";
+}
+
+static void show_box(int n)
+{
+	printk("show box %d: tic=\"%s\" tac=\"%s\" toe=\"%s\"\n",
+	       n, boxes[n]->tic, boxes[n]->tac, boxes[n]->toe);
+
+	if (strcmp(boxes[n]->tic, "tic") != 0 ||
+	    strcmp(boxes[n]->tac, "tac") != 0 ||
+	    strcmp(boxes[n]->toe, "toe") != 0) {
+		spooked = true;
+	}
+}
+
+void test_mempool_spook(void)
+{
+	struct k_mem_block block[9];
+	int i, ret;
+
+	printk("allocating boxes\n");
+	for (i = 0; i < 9; i++) {
+		ret = k_mem_pool_alloc(&my_pool, &block[i],
+				       sizeof(struct tic_tac_toe), 0);
+		zassert_false(ret != 0 || block[i].data == NULL,
+			      "memory allocation failure\n");
+		boxes[i] = block[i].data;
+	}
+
+	init_box(3);
+	show_box(3);
+	init_box(4);
+	show_box(4);
+	show_box(3); /* ! */
+	init_box(3);
+	show_box(3);
+	show_box(4); /* ! */
+
+	zassert_false(spooked, "");
+}