1 files changed, 156 insertions, 20 deletions

diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index 988267cc92c1..c1073d79e440 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -52,6 +52,8 @@ MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com>");
 
 torture_param(int, nwriters_stress, -1,
 	     "Number of write-locking stress-test threads");
+torture_param(int, nreaders_stress, -1,
+	     "Number of read-locking stress-test threads");
 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
 torture_param(int, onoff_interval, 0,
 	     "Time between CPU hotplugs (s), 0=disable");
@@ -74,15 +76,19 @@ static atomic_t n_lock_torture_errors;
 
 static struct task_struct *stats_task;
 static struct task_struct **writer_tasks;
+static struct task_struct **reader_tasks;
 
 static int nrealwriters_stress;
 static bool lock_is_write_held;
+static int nrealreaders_stress;
+static bool lock_is_read_held;
 
 struct lock_stress_stats {
 	long n_lock_fail;
 	long n_lock_acquired;
 };
 static struct lock_stress_stats *lwsa; /* writer statistics */
+static struct lock_stress_stats *lrsa; /* reader statistics */
 
 #if defined(MODULE)
 #define LOCKTORTURE_RUNNABLE_INIT 1
@@ -104,6 +110,9 @@ struct lock_torture_ops {
 	int (*writelock)(void);
 	void (*write_delay)(struct torture_random_state *trsp);
 	void (*writeunlock)(void);
+	int (*readlock)(void);
+	void (*read_delay)(struct torture_random_state *trsp);
+	void (*readunlock)(void);
 	unsigned long flags;
 	const char *name;
 };
@@ -142,6 +151,9 @@ static struct lock_torture_ops lock_busted_ops = {
 	.writelock	= torture_lock_busted_write_lock,
 	.write_delay	= torture_lock_busted_write_delay,
 	.writeunlock	= torture_lock_busted_write_unlock,
+	.readlock       = NULL,
+	.read_delay     = NULL,
+	.readunlock     = NULL,
 	.name		= "lock_busted"
 };
 
@@ -182,6 +194,9 @@ static struct lock_torture_ops spin_lock_ops = {
 	.writelock	= torture_spin_lock_write_lock,
 	.write_delay	= torture_spin_lock_write_delay,
 	.writeunlock	= torture_spin_lock_write_unlock,
+	.readlock       = NULL,
+	.read_delay     = NULL,
+	.readunlock     = NULL,
 	.name		= "spin_lock"
 };
 
@@ -205,6 +220,9 @@ static struct lock_torture_ops spin_lock_irq_ops = {
 	.writelock	= torture_spin_lock_write_lock_irq,
 	.write_delay	= torture_spin_lock_write_delay,
 	.writeunlock	= torture_lock_spin_write_unlock_irq,
+	.readlock       = NULL,
+	.read_delay     = NULL,
+	.readunlock     = NULL,
 	.name		= "spin_lock_irq"
 };
 
@@ -241,6 +259,9 @@ static struct lock_torture_ops mutex_lock_ops = {
 	.writelock	= torture_mutex_lock,
 	.write_delay	= torture_mutex_delay,
 	.writeunlock	= torture_mutex_unlock,
+	.readlock       = NULL,
+	.read_delay     = NULL,
+	.readunlock     = NULL,
 	.name		= "mutex_lock"
 };
 
@@ -274,28 +295,57 @@ static int lock_torture_writer(void *arg)
 }
 
 /*
+ * Lock torture reader kthread.  Repeatedly acquires and releases
+ * the reader lock.
+ */
+static int lock_torture_reader(void *arg)
+{
+	struct lock_stress_stats *lrsp = arg;
+	static DEFINE_TORTURE_RANDOM(rand);
+
+	VERBOSE_TOROUT_STRING("lock_torture_reader task started");
+	set_user_nice(current, MAX_NICE);
+
+	do {
+		if ((torture_random(&rand) & 0xfffff) == 0)
+			schedule_timeout_uninterruptible(1);
+		cur_ops->readlock();
+		lock_is_read_held = 1;
+		lrsp->n_lock_acquired++;
+		cur_ops->read_delay(&rand);
+		lock_is_read_held = 0;
+		cur_ops->readunlock();
+		stutter_wait("lock_torture_reader");
+	} while (!torture_must_stop());
+	torture_kthread_stopping("lock_torture_reader");
+	return 0;
+}
+
+/*
  * Create an lock-torture-statistics message in the specified buffer.
  */
-static void lock_torture_printk(char *page)
+static void __torture_print_stats(char *page,
+				  struct lock_stress_stats *statp, bool write)
 {
 	bool fail = 0;
-	int i;
+	int i, n_stress;
 	long max = 0;
-	long min = lwsa[0].n_lock_acquired;
+	long min = statp[0].n_lock_acquired;
 	long long sum = 0;
 
-	for (i = 0; i < nrealwriters_stress; i++) {
-		if (lwsa[i].n_lock_fail)
+	n_stress = write ? nrealwriters_stress : nrealreaders_stress;
+	for (i = 0; i < n_stress; i++) {
+		if (statp[i].n_lock_fail)
 			fail = true;
-		sum += lwsa[i].n_lock_acquired;
-		if (max < lwsa[i].n_lock_fail)
-			max = lwsa[i].n_lock_fail;
-		if (min > lwsa[i].n_lock_fail)
-			min = lwsa[i].n_lock_fail;
+		sum += statp[i].n_lock_acquired;
+		if (max < statp[i].n_lock_fail)
+			max = statp[i].n_lock_fail;
+		if (min > statp[i].n_lock_fail)
+			min = statp[i].n_lock_fail;
 	}
-	page += sprintf(page, "%s%s ", torture_type, TORTURE_FLAG);
 	page += sprintf(page,
-			"Writes:  Total: %lld  Max/Min: %ld/%ld %s  Fail: %d %s\n",
+			"%s:  Total: %lld  Max/Min: %ld/%ld %s  Fail: %d %s\n",
+			write ? "Writes" : "Reads ",
 			sum, max, min, max / 2 > min ? "???" : "",
 			fail, fail ? "!!!" : "");
 	if (fail)
@@ -315,15 +365,32 @@ static void lock_torture_stats_print(void)
 	int size = nrealwriters_stress * 200 + 8192;
 	char *buf;
 
+	if (cur_ops->readlock)
+		size += nrealreaders_stress * 200 + 8192;
+
 	buf = kmalloc(size, GFP_KERNEL);
 	if (!buf) {
 		pr_err("lock_torture_stats_print: Out of memory, need: %d",
 		       size);
 		return;
 	}
-	lock_torture_printk(buf);
+
+	__torture_print_stats(buf, lwsa, true);
 	pr_alert("%s", buf);
 	kfree(buf);
+
+	if (cur_ops->readlock) {
+		buf = kmalloc(size, GFP_KERNEL);
+		if (!buf) {
+			pr_err("lock_torture_stats_print: Out of memory, need: %d",
+			       size);
+			return;
+		}
+
+		__torture_print_stats(buf, lrsa, false);
+		pr_alert("%s", buf);
+		kfree(buf);
+	}
 }
 
 /*
@@ -350,10 +417,10 @@ lock_torture_print_module_parms(struct lock_torture_ops *cur_ops,
 				const char *tag)
 {
 	pr_alert("%s" TORTURE_FLAG
-		 "--- %s%s: nwriters_stress=%d stat_interval=%d verbose=%d shuffle_interval=%d stutter=%d shutdown_secs=%d onoff_interval=%d onoff_holdoff=%d\n",
+		 "--- %s%s: nwriters_stress=%d nreaders_stress=%d stat_interval=%d verbose=%d shuffle_interval=%d stutter=%d shutdown_secs=%d onoff_interval=%d onoff_holdoff=%d\n",
 		 torture_type, tag, debug_lock ? " [debug]": "",
-		 nrealwriters_stress, stat_interval, verbose,
-		 shuffle_interval, stutter, shutdown_secs,
+		 nrealwriters_stress, nrealreaders_stress, stat_interval,
+		 verbose, shuffle_interval, stutter, shutdown_secs,
 		 onoff_interval, onoff_holdoff);
 }
 
@@ -372,6 +439,14 @@ static void lock_torture_cleanup(void)
 		writer_tasks = NULL;
 	}
 
+	if (reader_tasks) {
+		for (i = 0; i < nrealreaders_stress; i++)
+			torture_stop_kthread(lock_torture_reader,
+					     reader_tasks[i]);
+		kfree(reader_tasks);
+		reader_tasks = NULL;
+	}
+
 	torture_stop_kthread(lock_torture_stats, stats_task);
 	lock_torture_stats_print();  /* -After- the stats thread is stopped! */
 
@@ -389,7 +464,7 @@ static void lock_torture_cleanup(void)
 
 static int __init lock_torture_init(void)
 {
-	int i;
+	int i, j;
 	int firsterr = 0;
 	static struct lock_torture_ops *torture_ops[] = {
 		&lock_busted_ops, &spin_lock_ops, &spin_lock_irq_ops, &mutex_lock_ops,
@@ -430,7 +505,6 @@ static int __init lock_torture_init(void)
 	if (strncmp(torture_type, "spin", 4) == 0)
 		debug_lock = true;
 #endif
-	lock_torture_print_module_parms(cur_ops, "Start of test");
 
 	/* Initialize the statistics so that each run gets its own numbers. */
 
@@ -446,8 +520,37 @@ static int __init lock_torture_init(void)
 		lwsa[i].n_lock_acquired = 0;
 	}
 
-	/* Start up the kthreads. */
+	if (cur_ops->readlock) {
+		if (nreaders_stress >= 0)
+			nrealreaders_stress = nreaders_stress;
+		else {
+			/*
+			 * By default distribute evenly the number of
+			 * readers and writers. We still run the same number
+			 * of threads as the writer-only locks default.
+			 */
+			if (nwriters_stress < 0) /* user doesn't care */
+				nrealwriters_stress = num_online_cpus();
+			nrealreaders_stress = nrealwriters_stress;
+		}
+
+		lock_is_read_held = 0;
+		lrsa = kmalloc(sizeof(*lrsa) * nrealreaders_stress, GFP_KERNEL);
+		if (lrsa == NULL) {
+			VERBOSE_TOROUT_STRING("lrsa: Out of memory");
+			firsterr = -ENOMEM;
+			kfree(lwsa);
+			goto unwind;
+		}
 
+		for (i = 0; i < nrealreaders_stress; i++) {
+			lrsa[i].n_lock_fail = 0;
+			lrsa[i].n_lock_acquired = 0;
+		}
+	}
+	lock_torture_print_module_parms(cur_ops, "Start of test");
+
+	/* Prepare torture context. */
 	if (onoff_interval > 0) {
 		firsterr = torture_onoff_init(onoff_holdoff * HZ,
 					      onoff_interval * HZ);
@@ -478,11 +581,44 @@ static int __init lock_torture_init(void)
 		firsterr = -ENOMEM;
 		goto unwind;
 	}
-	for (i = 0; i < nrealwriters_stress; i++) {
+
+	if (cur_ops->readlock) {
+		reader_tasks = kzalloc(nrealreaders_stress * sizeof(reader_tasks[0]),
+				       GFP_KERNEL);
+		if (reader_tasks == NULL) {
+			VERBOSE_TOROUT_ERRSTRING("reader_tasks: Out of memory");
+			firsterr = -ENOMEM;
+			goto unwind;
+		}
+	}
+
+	/*
+	 * Create the kthreads and start torturing (oh, those poor little locks).
+	 *
+	 * TODO: Note that we interleave writers with readers, giving writers a
+	 * slight advantage, by creating its kthread first. This can be modified
+	 * for very specific needs, or even let the user choose the policy, if
+	 * ever wanted.
+	 */
+	for (i = 0, j = 0; i < nrealwriters_stress ||
+		    j < nrealreaders_stress; i++, j++) {
+		if (i >= nrealwriters_stress)
+			goto create_reader;
+
+		/* Create writer. */
 		firsterr = torture_create_kthread(lock_torture_writer, &lwsa[i],
 						  writer_tasks[i]);
 		if (firsterr)
 			goto unwind;
+
+	create_reader:
+		if (cur_ops->readlock == NULL || (j >= nrealreaders_stress))
+			continue;
+		/* Create reader. */
+		firsterr = torture_create_kthread(lock_torture_reader, &lrsa[j],
+						  reader_tasks[j]);
+		if (firsterr)
+			goto unwind;
 	}
 	if (stat_interval > 0) {
 		firsterr = torture_create_kthread(lock_torture_stats, NULL,