locktorture: Support rwsems

We can easily do so with our new reader lock support. Just an arbitrary
design default: readers have higher (5x) critical region latencies than
writers: 50 ms and 10 ms, respectively.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

2 files changed, 69 insertions, 1 deletions

diff --git a/Documentation/locking/locktorture.txt b/Documentation/locking/locktorture.txt
index 7a72621b924f..be715015e0f7 100644
--- a/Documentation/locking/locktorture.txt
+++ b/Documentation/locking/locktorture.txt
@@ -47,6 +47,8 @@ torture_type	  Type of lock to torture. By default, only spinlocks will
 
                      o "mutex_lock": mutex_lock() and mutex_unlock() pairs.
 
+                     o "rwsem_lock": read/write down() and up() semaphore pairs.
+
 torture_runnable  Start locktorture at boot time in the case where the
                   module is built into the kernel, otherwise wait for
                   torture_runnable to be set via sysfs before starting.
diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index c1073d79e440..8480118c0ca8 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -265,6 +265,71 @@ static struct lock_torture_ops mutex_lock_ops = {
         .name           = "mutex_lock"
 };
 
+static DECLARE_RWSEM(torture_rwsem);
+static int torture_rwsem_down_write(void) __acquires(torture_rwsem)
+{
+        down_write(&torture_rwsem);
+        return 0;
+}
+
+static void torture_rwsem_write_delay(struct torture_random_state *trsp)
+{
+        const unsigned long longdelay_ms = 100;
+
+        /* We want a long delay occasionally to force massive contention.  */
+        if (!(torture_random(trsp) %
+              (nrealwriters_stress * 2000 * longdelay_ms)))
+                mdelay(longdelay_ms * 10);
+        else
+                mdelay(longdelay_ms / 10);
+#ifdef CONFIG_PREEMPT
+        if (!(torture_random(trsp) % (nrealwriters_stress * 20000)))
+                preempt_schedule();  /* Allow test to be preempted. */
+#endif
+}
+
+static void torture_rwsem_up_write(void) __releases(torture_rwsem)
+{
+        up_write(&torture_rwsem);
+}
+
+static int torture_rwsem_down_read(void) __acquires(torture_rwsem)
+{
+        down_read(&torture_rwsem);
+        return 0;
+}
+
+static void torture_rwsem_read_delay(struct torture_random_state *trsp)
+{
+        const unsigned long longdelay_ms = 100;
+
+        /* We want a long delay occasionally to force massive contention.  */
+        if (!(torture_random(trsp) %
+              (nrealwriters_stress * 2000 * longdelay_ms)))
+                mdelay(longdelay_ms * 2);
+        else
+                mdelay(longdelay_ms / 2);
+#ifdef CONFIG_PREEMPT
+        if (!(torture_random(trsp) % (nrealreaders_stress * 20000)))
+                preempt_schedule();  /* Allow test to be preempted. */
+#endif
+}
+
+static void torture_rwsem_up_read(void) __releases(torture_rwsem)
+{
+        up_read(&torture_rwsem);
+}
+
+static struct lock_torture_ops rwsem_lock_ops = {
+        .writelock      = torture_rwsem_down_write,
+        .write_delay    = torture_rwsem_write_delay,
+        .writeunlock    = torture_rwsem_up_write,
+        .readlock       = torture_rwsem_down_read,
+        .read_delay     = torture_rwsem_read_delay,
+        .readunlock     = torture_rwsem_up_read,
+        .name           = "rwsem_lock"
+};
+
 /*
  * Lock torture writer kthread.  Repeatedly acquires and releases
  * the lock, checking for duplicate acquisitions.
@@ -467,7 +532,8 @@ static int __init lock_torture_init(void)
         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,
+                &lock_busted_ops, &spin_lock_ops, &spin_lock_irq_ops,
+                &mutex_lock_ops, &rwsem_lock_ops,
         };
 
         if (!torture_init_begin(torture_type, verbose, &torture_runnable))