6893273 panic in fss_newpri() when scheduling class was changed

3 files changed, 21 insertions, 12 deletions

diff --git a/usr/src/uts/common/disp/fss.c b/usr/src/uts/common/disp/fss.c
index b051974669..62301d65d8 100644
--- a/usr/src/uts/common/disp/fss.c
+++ b/usr/src/uts/common/disp/fss.c
@@ -20,8 +20,7 @@
  */
 
 /*
- * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
- * Use is subject to license terms.
+ * Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved.
  */
 
 #include <sys/types.h>
@@ -1615,13 +1614,12 @@ fss_forkret(kthread_t *t, kthread_t *ct)
 	 * process does not disappear before we set it running.
 	 */
 	mutex_enter(&cp->p_lock);
-	mutex_exit(&pidlock);
 	continuelwps(cp);
 	mutex_exit(&cp->p_lock);
 
 	mutex_enter(&pp->p_lock);
+	mutex_exit(&pidlock);
 	continuelwps(pp);
-	mutex_exit(&pp->p_lock);
 
 	thread_lock(t);
 
@@ -1645,6 +1643,11 @@ fss_forkret(kthread_t *t, kthread_t *ct)
 		setfrontdq(t);
 
 	thread_unlock(t);
+	/*
+	 * Safe to drop p_lock now since it is safe to change
+	 * the scheduling class after this point.
+	 */
+	mutex_exit(&pp->p_lock);
 
 	swtch();
 }
diff --git a/usr/src/uts/common/disp/fx.c b/usr/src/uts/common/disp/fx.c
index dd6295074c..7e3607526b 100644
--- a/usr/src/uts/common/disp/fx.c
+++ b/usr/src/uts/common/disp/fx.c
@@ -20,8 +20,7 @@
  */
 
 /*
- * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
- * Use is subject to license terms.
+ * Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved.
  */
 
 #include <sys/types.h>
@@ -658,13 +657,12 @@ fx_forkret(kthread_t *t, kthread_t *ct)
 	 * the process does not disappear before we set it running.
 	 */
 	mutex_enter(&cp->p_lock);
-	mutex_exit(&pidlock);
 	continuelwps(cp);
 	mutex_exit(&cp->p_lock);
 
 	mutex_enter(&pp->p_lock);
+	mutex_exit(&pidlock);
 	continuelwps(pp);
-	mutex_exit(&pp->p_lock);
 
 	thread_lock(t);
 	fxpp = (fxproc_t *)(t->t_cldata);
@@ -673,6 +671,11 @@ fx_forkret(kthread_t *t, kthread_t *ct)
 	THREAD_TRANSITION(t);
 	fx_setrun(t);
 	thread_unlock(t);
+	/*
+	 * Safe to drop p_lock now since it is safe to change
+	 * the scheduling class after this point.
+	 */
+	mutex_exit(&pp->p_lock);
 
 	swtch();
 }
diff --git a/usr/src/uts/common/disp/ts.c b/usr/src/uts/common/disp/ts.c
index e8d1565276..05605be7f0 100644
--- a/usr/src/uts/common/disp/ts.c
+++ b/usr/src/uts/common/disp/ts.c
@@ -20,8 +20,7 @@
  */
 
 /*
- * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
- * Use is subject to license terms.
+ * Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved.
  */
 
 /*	Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
@@ -739,13 +738,12 @@ ts_forkret(kthread_t *t, kthread_t *ct)
 	 * the process does not disappear before we set it running.
 	 */
 	mutex_enter(&cp->p_lock);
-	mutex_exit(&pidlock);
 	continuelwps(cp);
 	mutex_exit(&cp->p_lock);
 
 	mutex_enter(&pp->p_lock);
+	mutex_exit(&pidlock);
 	continuelwps(pp);
-	mutex_exit(&pp->p_lock);
 
 	thread_lock(t);
 	tspp = (tsproc_t *)(t->t_cldata);
@@ -759,6 +757,11 @@ ts_forkret(kthread_t *t, kthread_t *ct)
 	THREAD_TRANSITION(t);
 	ts_setrun(t);
 	thread_unlock(t);
+	/*
+	 * Safe to drop p_lock now since since it is safe to change
+	 * the scheduling class after this point.
+	 */
+	mutex_exit(&pp->p_lock);
 
 	swtch();
 }