radix tree test suite: track preempt_count

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.

Link: http://lkml.kernel.org/r/1480369871-5271-39-git-send-email-mawilcox@linuxonhyperv.com
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Tested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 24 insertions, 13 deletions

diff --git a/tools/testing/radix-tree/linux.c b/tools/testing/radix-tree/linux.c
index 3cfb04e98e2f..1f32a16a3848 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 6210672e3baa..65c04c226965 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 daa9010693e8..64ffe67605d4 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);