linux-kernel - [PATCH v3 04/33] radix tree test suite: Track preempt

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Date:   Mon, 28 Nov 2016 13:50:42 -0800
From:   Matthew Wilcox <mawilcox@...uxonhyperv.com>
To:     linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Konstantin Khlebnikov <koct9i@...il.com>,
        Ross Zwisler <ross.zwisler@...ux.intel.com>
Cc:     Matthew Wilcox <willy@...radead.org>, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [PATCH v3 04/33] radix tree test suite: Track preempt_count

From: Matthew Wilcox <willy@...radead.org>

Rather than simply NOP out preempt_enable() and preempt_disable(),
keep track of preempt_count and display it regularly in case either
the test suite or the code under test is forgetting to balance the
enables & disables.  Only found a test-case that was forgetting to
re-enable preemption, but it's a possibility worth checking.

Signed-off-by: Matthew Wilcox <willy@...radead.org>
---
 tools/testing/radix-tree/linux.c         |  1 +
 tools/testing/radix-tree/linux/preempt.h |  6 +++---
 tools/testing/radix-tree/main.c          | 30 ++++++++++++++++++++----------
 3 files changed, 24 insertions(+), 13 deletions(-)

diff --git a/tools/testing/radix-tree/linux.c b/tools/testing/radix-tree/linux.c
index 3cfb04e..1f32a16 100644
--- a/tools/testing/radix-tree/linux.c
+++ b/tools/testing/radix-tree/linux.c
@@ -9,6 +9,7 @@
 #include <urcu/uatomic.h>
 
 int nr_allocated;
+int preempt_count;
 
 void *mempool_alloc(mempool_t *pool, int gfp_mask)
 {
diff --git a/tools/testing/radix-tree/linux/preempt.h b/tools/testing/radix-tree/linux/preempt.h
index 6210672..65c04c2 100644
--- a/tools/testing/radix-tree/linux/preempt.h
+++ b/tools/testing/radix-tree/linux/preempt.h
@@ -1,4 +1,4 @@
-/* */
+extern int preempt_count;
 
-#define preempt_disable() do { } while (0)
-#define preempt_enable() do { } while (0)
+#define preempt_disable()	uatomic_inc(&preempt_count)
+#define preempt_enable()	uatomic_dec(&preempt_count)
diff --git a/tools/testing/radix-tree/main.c b/tools/testing/radix-tree/main.c
index daa9010..64ffe67 100644
--- a/tools/testing/radix-tree/main.c
+++ b/tools/testing/radix-tree/main.c
@@ -293,27 +293,36 @@ static void single_thread_tests(bool long_run)
 {
 	int i;
 
-	printf("starting single_thread_tests: %d allocated\n", nr_allocated);
+	printf("starting single_thread_tests: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
 	multiorder_checks();
-	printf("after multiorder_check: %d allocated\n", nr_allocated);
+	printf("after multiorder_check: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
 	locate_check();
-	printf("after locate_check: %d allocated\n", nr_allocated);
+	printf("after locate_check: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
 	tag_check();
-	printf("after tag_check: %d allocated\n", nr_allocated);
+	printf("after tag_check: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
 	gang_check();
-	printf("after gang_check: %d allocated\n", nr_allocated);
+	printf("after gang_check: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
 	add_and_check();
-	printf("after add_and_check: %d allocated\n", nr_allocated);
+	printf("after add_and_check: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
 	dynamic_height_check();
-	printf("after dynamic_height_check: %d allocated\n", nr_allocated);
+	printf("after dynamic_height_check: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
 	big_gang_check(long_run);
-	printf("after big_gang_check: %d allocated\n", nr_allocated);
+	printf("after big_gang_check: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
 	for (i = 0; i < (long_run ? 2000 : 3); i++) {
 		copy_tag_check();
 		printf("%d ", i);
 		fflush(stdout);
 	}
-	printf("after copy_tag_check: %d allocated\n", nr_allocated);
+	printf("after copy_tag_check: %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
 }
 
 int main(int argc, char **argv)
@@ -336,7 +345,8 @@ int main(int argc, char **argv)
 	single_thread_tests(long_run);
 
 	sleep(1);
-	printf("after sleep(1): %d allocated\n", nr_allocated);
+	printf("after sleep(1): %d allocated, preempt %d\n",
+		nr_allocated, preempt_count);
 	rcu_unregister_thread();
 
 	exit(0);
-- 
2.10.2