linux-kernel - [PATCH] lib: add CONFIG_TEST_SORT to enable self-test of sort()

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Date:   Tue, 13 Dec 2016 20:42:27 +0000
From:   Felix Kostenzer <fkostenzer@...e.at>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Felix Kostenzer <fkostenzer@...e.at>
Subject: [PATCH] lib: add CONFIG_TEST_SORT to enable self-test of sort()

From: Kostenzer Felix <fkostenzer@...e.at>

along with the addition made to Kconfig.debug, the prior existing
but permanently disabled test function has been slightly refactored.

patch has been tested using QEMU 2.1.2 with a .config obtained
through 'make defconfig' (x86_64) and manually enabling the option.

Signed-off-by: Kostenzer Felix <fkostenzer@...e.at>
---
 lib/Kconfig.debug |  8 ++++++++
 lib/sort.c        | 41 ++++++++++++++++++++++++-----------------
 2 files changed, 32 insertions(+), 17 deletions(-)

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index a6c8db1..3f6b0ed 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1718,6 +1718,14 @@ config TEST_LIST_SORT
 
 	  If unsure, say N.
 
+config TEST_SORT
+	bool "Array-based sort test"
+	depends on DEBUG_KERNEL
+	help
+	  This option enables the self-test function of 'sort()' at boot.
+
+	  If unsure, say N.
+
 config KPROBES_SANITY_TEST
 	bool "Kprobes sanity tests"
 	depends on DEBUG_KERNEL
diff --git a/lib/sort.c b/lib/sort.c
index fc20df4..a9b156e 100644
--- a/lib/sort.c
+++ b/lib/sort.c
@@ -4,6 +4,8 @@
  * Jan 23 2005  Matt Mackall <mpm@...enic.com>
  */
 
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
 #include <linux/types.h>
 #include <linux/export.h>
 #include <linux/sort.h>
@@ -102,41 +104,46 @@ void sort(void *base, size_t num, size_t size,
 
 EXPORT_SYMBOL(sort);
 
-#if 0
+#ifdef CONFIG_TEST_SORT
 #include <linux/slab.h>
+#include <linux/module.h>
 /* a simple boot-time regression test */
 
-int cmpint(const void *a, const void *b)
+#define TEST_LEN 1000
+
+static int __init cmpint(const void *a, const void *b)
 {
 	return *(int *)a - *(int *)b;
 }
 
-static int sort_test(void)
+static int __init test_sort_init(void)
 {
-	int *a, i, r = 1;
-
-	a = kmalloc(1000 * sizeof(int), GFP_KERNEL);
-	BUG_ON(!a);
+	int *a, i, r = 1, err = -ENOMEM;
 
-	printk("testing sort()\n");
+	a = kmalloc_array(TEST_LEN, sizeof(*a), GFP_KERNEL);
+	if (!a)
+		return err;
 
-	for (i = 0; i < 1000; i++) {
+	for (i = 0; i < TEST_LEN; i++) {
 		r = (r * 725861) % 6599;
 		a[i] = r;
 	}
 
-	sort(a, 1000, sizeof(int), cmpint, NULL);
+	sort(a, TEST_LEN, sizeof(*a), cmpint, NULL);
 
-	for (i = 0; i < 999; i++)
+	err = -EINVAL;
+	for (i = 0; i < TEST_LEN-1; i++)
 		if (a[i] > a[i+1]) {
-			printk("sort() failed!\n");
-			break;
+			pr_err("test has failed\n");
+			goto exit;
 		}
-
+	err = 0;
+	pr_info("test passed\n");
+exit:
 	kfree(a);
-
-	return 0;
+	return err;
 }
 
-module_init(sort_test);
+module_init(test_sort_init);
+MODULE_LICENSE("GPL");
 #endif
-- 
2.1.4