- Add more strict in_atomic() checking to the mutex entry

function just to be extra safety and paranoid.

- Rewrite the thread shim to take full advantage of the
new kernel kthread API.  This greatly simplifies things.

- Add a new regression test for thread_exit() to ensure
it properly terminates a thread immediately without
allowing futher execution of the thread.



git-svn-id: https://outreach.scidac.gov/svn/spl/trunk@69 7e1ea52c-4ff2-0310-8f11-9dd32ca42a1c

modules/splat/splat-thread.c

@@ -6,7 +6,11 @@
 
 #define SPLAT_THREAD_TEST1_ID		0x0601
 #define SPLAT_THREAD_TEST1_NAME		"create"
-#define SPLAT_THREAD_TEST1_DESC		"Validate thread creation and destruction"
+#define SPLAT_THREAD_TEST1_DESC		"Validate thread creation"
+
+#define SPLAT_THREAD_TEST2_ID		0x0602
+#define SPLAT_THREAD_TEST2_NAME		"exit"
+#define SPLAT_THREAD_TEST2_DESC		"Validate thread exit"
 
 #define SPLAT_THREAD_TEST_MAGIC		0x4488CC00UL
 
@@ -18,24 +22,84 @@ typedef struct thread_priv {
 	int tp_rc;
 } thread_priv_t;
 
+static int
+splat_thread_rc(thread_priv_t *tp, int rc)
+{
+	int ret;
+
+	spin_lock(&tp->tp_lock);
+	ret = (tp->tp_rc == rc);
+	spin_unlock(&tp->tp_lock);
+
+	return ret;
+}
 
 static void
-splat_thread_work(void *priv)
+splat_thread_work1(void *priv)
 {
 	thread_priv_t *tp = (thread_priv_t *)priv;
 
 	spin_lock(&tp->tp_lock);
 	ASSERT(tp->tp_magic == SPLAT_THREAD_TEST_MAGIC);
 	tp->tp_rc = 1;
-
 	spin_unlock(&tp->tp_lock);
-	wake_up(&tp->tp_waitq);
 
+	wake_up(&tp->tp_waitq);
 	thread_exit();
 }
 
 static int
 splat_thread_test1(struct file *file, void *arg)
+{
+	thread_priv_t tp;
+        DEFINE_WAIT(wait);
+	kthread_t *thr;
+
+	tp.tp_magic = SPLAT_THREAD_TEST_MAGIC;
+	tp.tp_file = file;
+        spin_lock_init(&tp.tp_lock);
+	init_waitqueue_head(&tp.tp_waitq);
+	tp.tp_rc = 0;
+
+	thr = (kthread_t *)thread_create(NULL, 0, splat_thread_work1, &tp, 0,
+			                 &p0, TS_RUN, minclsyspri);
+	/* Must never fail under Solaris, but we check anyway since this
+	 * can happen in the linux SPL, we may want to change this behavior */
+	if (thr == NULL)
+		return  -ESRCH;
+
+	/* Sleep until the thread sets tp.tp_rc == 1 */
+	wait_event(tp.tp_waitq, splat_thread_rc(&tp, 1));
+
+        splat_vprint(file, SPLAT_THREAD_TEST1_NAME, "%s",
+	           "Thread successfully started properly\n");
+	return 0;
+}
+
+static void
+splat_thread_work2(void *priv)
+{
+	thread_priv_t *tp = (thread_priv_t *)priv;
+
+	spin_lock(&tp->tp_lock);
+	ASSERT(tp->tp_magic == SPLAT_THREAD_TEST_MAGIC);
+	tp->tp_rc = 1;
+	spin_unlock(&tp->tp_lock);
+
+	wake_up(&tp->tp_waitq);
+	thread_exit();
+
+	/* The following code is unreachable when thread_exit() is
+	 * working properly, which is exactly what we're testing */
+	spin_lock(&tp->tp_lock);
+	tp->tp_rc = 2;
+	spin_unlock(&tp->tp_lock);
+
+	wake_up(&tp->tp_waitq);
+}
+
+static int
+splat_thread_test2(struct file *file, void *arg)
 {
 	thread_priv_t tp;
         DEFINE_WAIT(wait);
@@ -48,32 +112,29 @@ splat_thread_test1(struct file *file, void *arg)
 	init_waitqueue_head(&tp.tp_waitq);
 	tp.tp_rc = 0;
 
-	spin_lock(&tp.tp_lock);
-
-	thr = (kthread_t *)thread_create(NULL, 0, splat_thread_work, &tp, 0,
+	thr = (kthread_t *)thread_create(NULL, 0, splat_thread_work2, &tp, 0,
 			                 &p0, TS_RUN, minclsyspri);
-	/* Must never fail under Solaris, but we check anyway so we can
-	 * report an error when this impossible thing happens */
-	if (thr == NULL) {
-		rc = -ESRCH;
-		goto out;
+	/* Must never fail under Solaris, but we check anyway since this
+	 * can happen in the linux SPL, we may want to change this behavior */
+	if (thr == NULL)
+		return  -ESRCH;
+
+	/* Sleep until the thread sets tp.tp_rc == 1 */
+	wait_event(tp.tp_waitq, splat_thread_rc(&tp, 1));
+
+	/* Sleep until the thread sets tp.tp_rc == 2, or until we hit
+	 * the timeout.  If thread exit is working properly we should
+	 * hit the timeout and never see to.tp_rc == 2. */
+	rc = wait_event_timeout(tp.tp_waitq, splat_thread_rc(&tp, 2), HZ / 10);
+	if (rc > 0) {
+		rc = -EINVAL;
+	        splat_vprint(file, SPLAT_THREAD_TEST2_NAME, "%s",
+		           "Thread did not exit properly at thread_exit()\n");
+	} else {
+	        splat_vprint(file, SPLAT_THREAD_TEST2_NAME, "%s",
+		           "Thread successfully exited at thread_exit()\n");
 	}
 
-        for (;;) {
-                prepare_to_wait(&tp.tp_waitq, &wait, TASK_UNINTERRUPTIBLE);
-                if (tp.tp_rc)
-                        break;
-
-                spin_unlock(&tp.tp_lock);
-                schedule();
-                spin_lock(&tp.tp_lock);
-        }
-
-        splat_vprint(file, SPLAT_THREAD_TEST1_NAME, "%s",
-	           "Thread successfully started and exited cleanly\n");
-out:
-	spin_unlock(&tp.tp_lock);
-
 	return rc;
 }
 
@@ -96,6 +157,8 @@ splat_thread_init(void)
 
         SPLAT_TEST_INIT(sub, SPLAT_THREAD_TEST1_NAME, SPLAT_THREAD_TEST1_DESC,
                       SPLAT_THREAD_TEST1_ID, splat_thread_test1);
+        SPLAT_TEST_INIT(sub, SPLAT_THREAD_TEST2_NAME, SPLAT_THREAD_TEST2_DESC,
+                      SPLAT_THREAD_TEST2_ID, splat_thread_test2);
 
         return sub;
 }
@@ -104,6 +167,7 @@ void
 splat_thread_fini(splat_subsystem_t *sub)
 {
         ASSERT(sub);
+        SPLAT_TEST_FINI(sub, SPLAT_THREAD_TEST2_ID);
         SPLAT_TEST_FINI(sub, SPLAT_THREAD_TEST1_ID);
 
         kfree(sub);