PERFORCE change 134101 for review

[John Baldwin]

http://perforce.freebsd.org/chv.cgi?CH=134101

Change 134101 by jhb at jhb_mutex on 2008/01/25 19:59:58

	- Add an assert to enforce MTX_RECURSE checking for spin mutexes
	  (previously this was only done with WITNESS, but hardly anyone
	   enables WITNESS on spin locks)
	- Add test cases for MTX_RECURSE testing for spin locks and a test
	  case for the sleepq chain lock recursing.

Affected files ...

.. //depot/projects/smpng/sys/kern/kern_mutex.c#150 edit
.. //depot/projects/smpng/sys/modules/crash/crash.c#49 edit

Differences ...

==== //depot/projects/smpng/sys/kern/kern_mutex.c#150 (text+ko) ====

@@ -216,6 +216,10 @@
 	KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
 	    ("mtx_lock_spin() of sleep mutex %s @ %s:%d",
 	    m->lock_object.lo_name, file, line));
+	if (mtx_owned(m))
+		KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0,
+	    ("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n",
+		    m->lock_object.lo_name, file, line));
 	WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE,
 	    file, line);
 	_get_spin_lock(m, curthread, opts, file, line);

==== //depot/projects/smpng/sys/modules/crash/crash.c#49 (text+ko) ====

@@ -100,6 +100,18 @@
 }
 
 static void
+exercise_sc_recurse(void)
+{
+	struct callout c;
+
+	callout_init(&c, CALLOUT_MPSAFE);
+	callout_reset(&c, hz, tsleep_race_fallback, NULL);
+	tsleep(&race_wchan, 0, "race", 5 * hz);
+	callout_drain(&c);
+}
+CRASH_EVENT("test recursing on sleepq chain lock", exercise_sc_recurse);
+
+static void
 exercise_tsleep_race(void)
 {
 	struct callout c;
@@ -160,6 +172,30 @@
 CRASH_EVENT("exercise tsleep() race", exercise_tsleep_race);
 
 static void
+spin_recurse(void)
+{
+	
+	bzero(&test1_mtx, sizeof(test1_mtx));
+	mtx_init(&test1_mtx, "test1", NULL, MTX_SPIN | MTX_RECURSE);
+	mtx_lock_spin(&test1_mtx);
+	mtx_lock_spin(&test1_mtx);
+	kdb_enter(KDB_WHY_CRASH, "test1_mtx should be recursed");
+	mtx_unlock_spin(&test1_mtx);
+	mtx_unlock_spin(&test1_mtx);
+	mtx_destroy(&test1_mtx);
+
+	bzero(&test1_mtx, sizeof(test1_mtx));
+	mtx_init(&test1_mtx, "test1", NULL, MTX_SPIN);
+	printf("recursing on non-recursive spin lock should go boom\n");
+	mtx_lock_spin(&test1_mtx);
+	mtx_lock_spin(&test1_mtx);
+	mtx_unlock_spin(&test1_mtx);
+	mtx_unlock_spin(&test1_mtx);
+	mtx_destroy(&test1_mtx);
+}
+CRASH_EVENT("test spin lock recurse", spin_recurse);
+
+static void
 sx_recurse(void)
 {