From: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Date: Wed, 24 Apr 2013 00:05:42 +0000 (-0700)
Subject: rcu: Add duplicate-callback tests to rcutorture
X-Git-Tag: next-20130607~35^2~4
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=86cac1d6e1bf16b193be4f10e1fa4ad528ec3718;p=karo-tx-linux.git

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 b1fa5510388d..193e17b77408 100644
--- 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;