2 files changed, 84 insertions, 13 deletions

diff --git a/Documentation/RCU/torture.txt b/Documentation/RCU/torture.txt
index 516527d4bc55..a342b6e1cc10 100644
--- a/Documentation/RCU/torture.txt
+++ b/Documentation/RCU/torture.txt
@@ -30,10 +30,10 @@ MODULE PARAMETERS
 
 This module has the following parameters:
 
-nreaders        This is the number of RCU reading threads supported.
-                The default is twice the number of CPUs.  Why twice?
-                To properly exercise RCU implementations with preemptible
-                read-side critical sections.
+irqreaders      Says to invoke RCU readers from irq level.  This is currently
+                done via timers.  Defaults to "1" for variants of RCU that
+                permit this.  (Or, more accurately, variants of RCU that do
+                -not- permit this know to ignore this variable.)
 
 nfakewriters    This is the number of RCU fake writer threads to run.  Fake
                 writer threads repeatedly use the synchronous "wait for
@@ -44,6 +44,16 @@ nfakewriters	This is the number of RCU fake writer threads to run.  Fake
                 to trigger special cases caused by multiple writers, such as
                 the synchronize_srcu() early return optimization.
 
+nreaders        This is the number of RCU reading threads supported.
+                The default is twice the number of CPUs.  Why twice?
+                To properly exercise RCU implementations with preemptible
+                read-side critical sections.
+
+shuffle_interval
+                The number of seconds to keep the test threads affinitied
+                to a particular subset of the CPUs, defaults to 3 seconds.
+                Used in conjunction with test_no_idle_hz.
+
 stat_interval   The number of seconds between output of torture
                 statistics (via printk()).  Regardless of the interval,
                 statistics are printed when the module is unloaded.
@@ -51,11 +61,6 @@ stat_interval	The number of seconds between output of torture
                 be printed -only- when the module is unloaded, and this
                 is the default.
 
-shuffle_interval
-                The number of seconds to keep the test threads affinitied
-                to a particular subset of the CPUs, defaults to 3 seconds.
-                Used in conjunction with test_no_idle_hz.
-
 stutter         The length of time to run the test before pausing for this
                 same period of time.  Defaults to "stutter=5", so as
                 to run and pause for (roughly) five-second intervals.
diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index 5e954edf0ed5..90b5b123f7a1 100644
--- a/kernel/rcutorture.c
+++ b/kernel/rcutorture.c
@@ -59,6 +59,7 @@ static int verbose;		/* Print more debug info. */
 static int test_no_idle_hz;     /* Test RCU's support for tickless idle CPUs. */
 static int shuffle_interval = 3; /* Interval between shuffles (in sec)*/
 static int stutter = 5;         /* Start/stop testing interval (in sec) */
+static int irqreader = 1;       /* RCU readers from irq (timers). */
 static char *torture_type = "rcu"; /* What RCU implementation to torture. */
 
 module_param(nreaders, int, 0444);
@@ -75,6 +76,8 @@ module_param(shuffle_interval, int, 0444);
 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
 module_param(stutter, int, 0444);
 MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
+module_param(irqreader, int, 0444);
+MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
 module_param(torture_type, charp, 0444);
 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
 
@@ -121,6 +124,7 @@ 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 struct list_head rcu_torture_removed;
 
 static int stutter_pause_test = 0;
@@ -217,6 +221,7 @@ struct rcu_torture_ops {
         void (*sync)(void);
         void (*cb_barrier)(void);
         int (*stats)(char *page);
+        int irqcapable;
         char *name;
 };
 static struct rcu_torture_ops *cur_ops = NULL;
@@ -291,6 +296,7 @@ static struct rcu_torture_ops rcu_ops = {
         .sync = synchronize_rcu,
         .cb_barrier = rcu_barrier,
         .stats = NULL,
+        .irqcapable = 1,
         .name = "rcu"
 };
 
@@ -331,6 +337,7 @@ static struct rcu_torture_ops rcu_sync_ops = {
         .sync = synchronize_rcu,
         .cb_barrier = NULL,
         .stats = NULL,
+        .irqcapable = 1,
         .name = "rcu_sync"
 };
 
@@ -392,6 +399,7 @@ static struct rcu_torture_ops rcu_bh_ops = {
         .sync = rcu_bh_torture_synchronize,
         .cb_barrier = rcu_barrier_bh,
         .stats = NULL,
+        .irqcapable = 1,
         .name = "rcu_bh"
 };
 
@@ -406,6 +414,7 @@ static struct rcu_torture_ops rcu_bh_sync_ops = {
         .sync = rcu_bh_torture_synchronize,
         .cb_barrier = NULL,
         .stats = NULL,
+        .irqcapable = 1,
         .name = "rcu_bh_sync"
 };
 
@@ -532,6 +541,7 @@ static struct rcu_torture_ops sched_ops = {
         .sync = sched_torture_synchronize,
         .cb_barrier = rcu_barrier_sched,
         .stats = NULL,
+        .irqcapable = 1,
         .name = "sched"
 };
 
@@ -620,6 +630,52 @@ rcu_torture_fakewriter(void *arg)
 }
 
 /*
+ * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
+ * incrementing the corresponding element of the pipeline array.  The
+ * counter in the element should never be greater than 1, otherwise, the
+ * RCU implementation is broken.
+ */
+static void rcu_torture_timer(unsigned long unused)
+{
+        int idx;
+        int completed;
+        static DEFINE_RCU_RANDOM(rand);
+        static DEFINE_SPINLOCK(rand_lock);
+        struct rcu_torture *p;
+        int pipe_count;
+
+        idx = cur_ops->readlock();
+        completed = cur_ops->completed();
+        p = rcu_dereference(rcu_torture_current);
+        if (p == NULL) {
+                /* Leave because rcu_torture_writer is not yet underway */
+                cur_ops->readunlock(idx);
+                return;
+        }
+        if (p->rtort_mbtest == 0)
+                atomic_inc(&n_rcu_torture_mberror);
+        spin_lock(&rand_lock);
+        cur_ops->readdelay(&rand);
+        n_rcu_torture_timers++;
+        spin_unlock(&rand_lock);
+        preempt_disable();
+        pipe_count = p->rtort_pipe_count;
+        if (pipe_count > RCU_TORTURE_PIPE_LEN) {
+                /* Should not happen, but... */
+                pipe_count = RCU_TORTURE_PIPE_LEN;
+        }
+        ++__get_cpu_var(rcu_torture_count)[pipe_count];
+        completed = cur_ops->completed() - completed;
+        if (completed > RCU_TORTURE_PIPE_LEN) {
+                /* Should not happen, but... */
+                completed = RCU_TORTURE_PIPE_LEN;
+        }
+        ++__get_cpu_var(rcu_torture_batch)[completed];
+        preempt_enable();
+        cur_ops->readunlock(idx);
+}
+
+/*
  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
  * incrementing the corresponding element of the pipeline array.  The
  * counter in the element should never be greater than 1, otherwise, the
@@ -633,11 +689,18 @@ rcu_torture_reader(void *arg)
         DEFINE_RCU_RANDOM(rand);
         struct rcu_torture *p;
         int pipe_count;
+        struct timer_list t;
 
         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
         set_user_nice(current, 19);
+        if (irqreader && cur_ops->irqcapable)
+                setup_timer_on_stack(&t, rcu_torture_timer, 0);
 
         do {
+                if (irqreader && cur_ops->irqcapable) {
+                        if (!timer_pending(&t))
+                                mod_timer(&t, 1);
+                }
                 idx = cur_ops->readlock();
                 completed = cur_ops->completed();
                 p = rcu_dereference(rcu_torture_current);
@@ -669,6 +732,8 @@ rcu_torture_reader(void *arg)
                 rcu_stutter_wait();
         } while (!kthread_should_stop() && !fullstop);
         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
+        if (irqreader && cur_ops->irqcapable)
+                del_timer_sync(&t);
         while (!kthread_should_stop())
                 schedule_timeout_uninterruptible(1);
         return 0;
@@ -699,14 +764,15 @@ rcu_torture_printk(char *page)
         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
         cnt += sprintf(&page[cnt],
                        "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
-                       "rtmbe: %d",
+                       "rtmbe: %d nt: %ld",
                        rcu_torture_current,
                        rcu_torture_current_version,
                        list_empty(&rcu_torture_freelist),
                        atomic_read(&n_rcu_torture_alloc),
                        atomic_read(&n_rcu_torture_alloc_fail),
                        atomic_read(&n_rcu_torture_free),
-                       atomic_read(&n_rcu_torture_mberror));
+                       atomic_read(&n_rcu_torture_mberror),
+                       n_rcu_torture_timers);
         if (atomic_read(&n_rcu_torture_mberror) != 0)
                 cnt += sprintf(&page[cnt], " !!!");
         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
@@ -862,10 +928,10 @@ rcu_torture_print_module_parms(char *tag)
         printk(KERN_ALERT "%s" TORTURE_FLAG
                 "--- %s: nreaders=%d nfakewriters=%d "
                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
-                "shuffle_interval=%d stutter=%d\n",
+                "shuffle_interval=%d stutter=%d irqreader=%d\n",
                 torture_type, tag, nrealreaders, nfakewriters,
                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
-                stutter);
+                stutter, irqreader);
 }
 
 static void