rcu: Add duplicate-callback tests to rcutorture

This commit adds a object_debug option to rcutorture to allow the
debug-object-based checks for duplicate call_rcu() invocations to
be deterministically tested.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>

diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index b1fa5510388d12ff95afa6f38a090956551a5907..193e17b77408ebd73b2e6b8f66fec308f11e1726 100644 (file)
--- a/kernel/rcutorture.c
+++ b/kernel/rcutorture.c
@@ -66,6 +66,7 @@ static int fqs_duration;      /* Duration of bursts (us), 0 to disable. */
 static int fqs_holdoff;                /* Hold time within burst (us). */
 static int fqs_stutter = 3;    /* Wait time between bursts (s). */
 static int n_barrier_cbs;      /* Number of callbacks to test RCU barriers. */
+static int object_debug;       /* Test object-debug double call_rcu()?. */
 static int onoff_interval;     /* Wait time between CPU hotplugs, 0=disable. */
 static int onoff_holdoff;      /* Seconds after boot before CPU hotplugs. */
 static int shutdown_secs;      /* Shutdown time (s).  <=0 for no shutdown. */
@@ -100,6 +101,8 @@ module_param(fqs_stutter, int, 0444);
 MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
 module_param(n_barrier_cbs, int, 0444);
 MODULE_PARM_DESC(n_barrier_cbs, "# of callbacks/kthreads for barrier testing");
+module_param(object_debug, int, 0444);
+MODULE_PARM_DESC(object_debug, "Enable debug-object double call_rcu() testing");
 module_param(onoff_interval, int, 0444);
 MODULE_PARM_DESC(onoff_interval, "Time between CPU hotplugs (s), 0=disable");
 module_param(onoff_holdoff, int, 0444);
@@ -1934,6 +1937,18 @@ rcu_torture_cleanup(void)
                rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
 }
 
+#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
+static void rcu_torture_leak_cb(struct rcu_head *rhp)
+{
+}
+
+static void rcu_torture_err_cb(struct rcu_head *rhp)
+{
+       /* This -might- happen due to race conditions, but is unlikely. */
+       pr_alert("rcutorture: duplicated callback was invoked.\n");
+}
+#endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
+
 static int __init
 rcu_torture_init(void)
 {
@@ -2163,6 +2178,28 @@ rcu_torture_init(void)
                firsterr = retval;
                goto unwind;
        }
+       if (object_debug) {
+#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
+               struct rcu_head rh1;
+               struct rcu_head rh2;
+
+               init_rcu_head_on_stack(&rh1);
+               init_rcu_head_on_stack(&rh2);
+               pr_alert("rcutorture: WARN: Duplicate call_rcu() test starting.\n");
+               local_irq_disable(); /* Make it hard to finish grace period. */
+               call_rcu(&rh1, rcu_torture_leak_cb); /* start grace period. */
+               call_rcu(&rh2, rcu_torture_err_cb);
+               call_rcu(&rh2, rcu_torture_err_cb); /* duplicate callback. */
+               local_irq_enable();
+               rcu_barrier();
+               pr_alert("rcutorture: WARN: Duplicate call_rcu() test complete.\n");
+               destroy_rcu_head_on_stack(&rh1);
+               destroy_rcu_head_on_stack(&rh2);
+#else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
+               pr_alert("rcutorture: !%s, not testing duplicate call_rcu()\n",
+                        "CONFIG_DEBUG_OBJECTS_RCU_HEAD");
+#endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
+       }
        rcutorture_record_test_transition();
        mutex_unlock(&fullstop_mutex);
        return 0;