[19/29] radix tree test suite: iteration test misuses RCU
diff mbox

Message ID 1479341856-30320-58-git-send-email-mawilcox@linuxonhyperv.com
State New
Headers show

Commit Message

Matthew Wilcox Nov. 17, 2016, 12:17 a.m. UTC
From: Matthew Wilcox <mawilcox@microsoft.com>

Each thread needs to register itself with RCU, otherwise the reading
thread's read lock has no effect and the freeing thread will free the
memory in the tree without waiting for the read lock to be dropped.

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
---
 tools/testing/radix-tree/iteration_check.c | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

Patch
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diff --git a/tools/testing/radix-tree/iteration_check.c b/tools/testing/radix-tree/iteration_check.c
index 11d570c..df71cb8 100644
--- a/tools/testing/radix-tree/iteration_check.c
+++ b/tools/testing/radix-tree/iteration_check.c
@@ -29,6 +29,8 @@  static void *add_entries_fn(void *arg)
 {
 	int pgoff;
 
+	rcu_register_thread();
+
 	while (!test_complete) {
 		for (pgoff = 0; pgoff < 100; pgoff++) {
 			pthread_mutex_lock(&tree_lock);
@@ -38,6 +40,8 @@  static void *add_entries_fn(void *arg)
 		}
 	}
 
+	rcu_unregister_thread();
+
 	return NULL;
 }
 
@@ -53,6 +57,8 @@  static void *tagged_iteration_fn(void *arg)
 	struct radix_tree_iter iter;
 	void **slot;
 
+	rcu_register_thread();
+
 	while (!test_complete) {
 		rcu_read_lock();
 		radix_tree_for_each_tagged(slot, &tree, &iter, 0, TAG) {
@@ -72,12 +78,18 @@  static void *tagged_iteration_fn(void *arg)
 				continue;
 			}
 
-			if (rand_r(&seeds[0]) % 50 == 0)
+			if (rand_r(&seeds[0]) % 50 == 0) {
 				slot = radix_tree_iter_next(&iter);
+				rcu_read_unlock();
+				rcu_barrier();
+				rcu_read_lock();
+			}
 		}
 		rcu_read_unlock();
 	}
 
+	rcu_unregister_thread();
+
 	return NULL;
 }
 
@@ -93,6 +105,8 @@  static void *untagged_iteration_fn(void *arg)
 	struct radix_tree_iter iter;
 	void **slot;
 
+	rcu_register_thread();
+
 	while (!test_complete) {
 		rcu_read_lock();
 		radix_tree_for_each_slot(slot, &tree, &iter, 0) {
@@ -112,12 +126,18 @@  static void *untagged_iteration_fn(void *arg)
 				continue;
 			}
 
-			if (rand_r(&seeds[1]) % 50 == 0)
+			if (rand_r(&seeds[1]) % 50 == 0) {
 				slot = radix_tree_iter_next(&iter);
+				rcu_read_unlock();
+				rcu_barrier();
+				rcu_read_lock();
+			}
 		}
 		rcu_read_unlock();
 	}
 
+	rcu_unregister_thread();
+
 	return NULL;
 }
 
@@ -127,6 +147,8 @@  static void *untagged_iteration_fn(void *arg)
  */
 static void *remove_entries_fn(void *arg)
 {
+	rcu_register_thread();
+
 	while (!test_complete) {
 		int pgoff;
 
@@ -137,6 +159,8 @@  static void *remove_entries_fn(void *arg)
 		pthread_mutex_unlock(&tree_lock);
 	}
 
+	rcu_unregister_thread();
+
 	return NULL;
 }