linux-kernel - [PATCH tip/core/rcu 4/4] rcu: Add duplicate-callback tests to rcutorture

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Message-Id: <1366763626-16712-4-git-send-email-paulmck@linux.vnet.ibm.com>
Date:	Tue, 23 Apr 2013 17:33:46 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	linux-kernel@...r.kernel.org
Cc:	mingo@...e.hu, laijs@...fujitsu.com, dipankar@...ibm.com,
	akpm@...ux-foundation.org, mathieu.desnoyers@...ymtl.ca,
	josh@...htriplett.org, niv@...ibm.com, tglx@...utronix.de,
	peterz@...radead.org, rostedt@...dmis.org, Valdis.Kletnieks@...edu,
	dhowells@...hat.com, edumazet@...gle.com, darren@...art.com,
	fweisbec@...il.com, sbw@....edu,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Sedat Dilek <sedat.dilek@...il.com>,
	Davidlohr Bueso <davidlohr.bueso@...com>,
	Rik van Riel <riel@...riel.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH tip/core/rcu 4/4] rcu: Add duplicate-callback tests to rcutorture

From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>

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@...ux.vnet.ibm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: Sedat Dilek <sedat.dilek@...il.com>
Cc: Davidlohr Bueso <davidlohr.bueso@...com>
Cc: Rik van Riel <riel@...riel.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
---
 kernel/rcutorture.c | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index b1fa551..2f34ebf 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: 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: 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;
-- 
1.8.1.5

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