1 files changed, 25 insertions, 22 deletions

diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index b33db539a8ad..697c0a0229d4 100644
--- a/kernel/rcutorture.c
+++ b/kernel/rcutorture.c
@@ -18,7 +18,7 @@
  * Copyright (C) IBM Corporation, 2005, 2006
  *
  * Authors: Paul E. McKenney <paulmck@us.ibm.com>
- *          Josh Triplett <josh@freedesktop.org>
+ *        Josh Triplett <josh@freedesktop.org>
  *
  * See also:  Documentation/RCU/torture.txt
  */
@@ -50,7 +50,7 @@
 
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and "
-              "Josh Triplett <josh@freedesktop.org>");
+              "Josh Triplett <josh@freedesktop.org>");
 
 static int nreaders = -1;       /* # reader threads, defaults to 2*ncpus */
 static int nfakewriters = 4;    /* # fake writer threads */
@@ -110,8 +110,8 @@ struct rcu_torture {
 };
 
 static LIST_HEAD(rcu_torture_freelist);
-static struct rcu_torture *rcu_torture_current = NULL;
-static long rcu_torture_current_version = 0;
+static struct rcu_torture *rcu_torture_current;
+static long rcu_torture_current_version;
 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 static DEFINE_SPINLOCK(rcu_torture_lock);
 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
@@ -124,11 +124,11 @@ static atomic_t n_rcu_torture_alloc_fail;
 static atomic_t n_rcu_torture_free;
 static atomic_t n_rcu_torture_mberror;
 static atomic_t n_rcu_torture_error;
-static long n_rcu_torture_timers = 0;
+static long n_rcu_torture_timers;
 static struct list_head rcu_torture_removed;
 static cpumask_var_t shuffle_tmp_mask;
 
-static int stutter_pause_test = 0;
+static int stutter_pause_test;
 
 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 #define RCUTORTURE_RUNNABLE_INIT 1
@@ -267,7 +267,8 @@ struct rcu_torture_ops {
         int irq_capable;
         char *name;
 };
-static struct rcu_torture_ops *cur_ops = NULL;
+
+static struct rcu_torture_ops *cur_ops;
 
 /*
  * Definitions for rcu torture testing.
@@ -281,14 +282,17 @@ static int rcu_torture_read_lock(void) __acquires(RCU)
 
 static void rcu_read_delay(struct rcu_random_state *rrsp)
 {
-        long delay;
-        const long longdelay = 200;
+        const unsigned long shortdelay_us = 200;
+        const unsigned long longdelay_ms = 50;
 
-        /* We want there to be long-running readers, but not all the time. */
+        /* We want a short delay sometimes to make a reader delay the grace
+         * period, and we want a long delay occasionally to trigger
+         * force_quiescent_state. */
 
-        delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay);
-        if (!delay)
-                udelay(longdelay);
+        if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
+                mdelay(longdelay_ms);
+        if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
+                udelay(shortdelay_us);
 }
 
 static void rcu_torture_read_unlock(int idx) __releases(RCU)
@@ -339,8 +343,8 @@ static struct rcu_torture_ops rcu_ops = {
         .sync           = synchronize_rcu,
         .cb_barrier     = rcu_barrier,
         .stats          = NULL,
-        .irq_capable    = 1,
-        .name           = "rcu"
+        .irq_capable    = 1,
+        .name           = "rcu"
 };
 
 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
@@ -602,8 +606,6 @@ static struct rcu_torture_ops sched_ops_sync = {
         .name           = "sched_sync"
 };
 
-extern int rcu_expedited_torture_stats(char *page);
-
 static struct rcu_torture_ops sched_expedited_ops = {
         .init           = rcu_sync_torture_init,
         .cleanup        = NULL,
@@ -638,14 +640,15 @@ rcu_torture_writer(void *arg)
 
         do {
                 schedule_timeout_uninterruptible(1);
-                if ((rp = rcu_torture_alloc()) == NULL)
+                rp = rcu_torture_alloc();
+                if (rp == NULL)
                         continue;
                 rp->rtort_pipe_count = 0;
                 udelay(rcu_random(&rand) & 0x3ff);
                 old_rp = rcu_torture_current;
                 rp->rtort_mbtest = 1;
                 rcu_assign_pointer(rcu_torture_current, rp);
-                smp_wmb();
+                smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
                 if (old_rp) {
                         i = old_rp->rtort_pipe_count;
                         if (i > RCU_TORTURE_PIPE_LEN)
@@ -1110,7 +1113,7 @@ rcu_torture_init(void)
                 printk(KERN_ALERT "rcutorture: invalid torture type: \"%s\"\n",
                        torture_type);
                 mutex_unlock(&fullstop_mutex);
-                return (-EINVAL);
+                return -EINVAL;
         }
         if (cur_ops->init)
                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
@@ -1161,7 +1164,7 @@ rcu_torture_init(void)
                 goto unwind;
         }
         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
-                                   GFP_KERNEL);
+                                   GFP_KERNEL);
         if (fakewriter_tasks == NULL) {
                 VERBOSE_PRINTK_ERRSTRING("out of memory");
                 firsterr = -ENOMEM;
@@ -1170,7 +1173,7 @@ rcu_torture_init(void)
         for (i = 0; i < nfakewriters; i++) {
                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
-                                                  "rcu_torture_fakewriter");
+                                                  "rcu_torture_fakewriter");
                 if (IS_ERR(fakewriter_tasks[i])) {
                         firsterr = PTR_ERR(fakewriter_tasks[i]);
                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");