rcutorture: Abstract torture_shutdown_absorb()

Because handling races between rmmod and normal shutdown is not specific
to rcutorture, this commit renames rcutorture_shutdown_absorb() to
torture_shutdown_absorb() and pulls it out into then kernel/torture.c
module.  This implies pulling the fullstop mechanism into kernel/torture.c
as well.

The exporting of fullstop and fullstop_mutex is ugly and must die.
And it does in fact die in later commits that introduce higher-level
APIs that encapsulate both of these variables.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>`

1 files changed, 18 insertions, 39 deletions

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 86fd8c11257b..a868758a6f9c 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -91,11 +91,15 @@ torture_param(int, test_boost_interval, 7,
              "Interval between boost tests, seconds.");
 torture_param(bool, test_no_idle_hz, true,
              "Test support for tickless idle CPUs");
-torture_param(bool, verbose, false, "Enable verbose debugging printk()s");
 
-static char *torture_type = "rcu";
+char *torture_type = "rcu";
+EXPORT_SYMBOL_GPL(torture_type);
 module_param(torture_type, charp, 0444);
 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, ...)");
+bool verbose;
+EXPORT_SYMBOL_GPL(verbose);
+module_param(verbose, bool, 0444);
+MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
 
 static int nrealreaders;
 static struct task_struct *writer_task;
@@ -200,17 +204,6 @@ static atomic_t barrier_cbs_invoked;	/* Barrier callbacks invoked. */
 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 
-/* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
-
-#define FULLSTOP_DONTSTOP 0     /* Normal operation. */
-#define FULLSTOP_SHUTDOWN 1     /* System shutdown with rcutorture running. */
-#define FULLSTOP_RMMOD    2     /* Normal rmmod of rcutorture. */
-static int fullstop = FULLSTOP_RMMOD;
-/*
- * Protect fullstop transitions and spawning of kthreads.
- */
-static DEFINE_MUTEX(fullstop_mutex);
-
 /* Forward reference. */
 static void rcu_torture_cleanup(void);
 
@@ -232,20 +225,6 @@ rcutorture_shutdown_notify(struct notifier_block *unused1,
 }
 
 /*
- * Absorb kthreads into a kernel function that won't return, so that
- * they won't ever access module text or data again.
- */
-static void rcutorture_shutdown_absorb(const char *title)
-{
-        if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
-                pr_notice(
-                       "rcutorture thread %s parking due to system shutdown\n",
-                       title);
-                schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
-        }
-}
-
-/*
  * Allocate an element from the rcu_tortures pool.
  */
 static struct rcu_torture *
@@ -286,7 +265,7 @@ rcu_stutter_wait(const char *title)
                         schedule_timeout_interruptible(1);
                 else
                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
-                rcutorture_shutdown_absorb(title);
+                torture_shutdown_absorb(title);
         }
 }
 
@@ -681,7 +660,7 @@ checkwait:	rcu_stutter_wait("rcu_torture_boost");
 
         /* Clean up and exit. */
         VERBOSE_TOROUT_STRING("rcu_torture_boost task stopping");
-        rcutorture_shutdown_absorb("rcu_torture_boost");
+        torture_shutdown_absorb("rcu_torture_boost");
         while (!kthread_should_stop() || rbi.inflight)
                 schedule_timeout_uninterruptible(1);
         smp_mb(); /* order accesses to ->inflight before stack-frame death. */
@@ -717,7 +696,7 @@ rcu_torture_fqs(void *arg)
                 rcu_stutter_wait("rcu_torture_fqs");
         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
         VERBOSE_TOROUT_STRING("rcu_torture_fqs task stopping");
-        rcutorture_shutdown_absorb("rcu_torture_fqs");
+        torture_shutdown_absorb("rcu_torture_fqs");
         while (!kthread_should_stop())
                 schedule_timeout_uninterruptible(1);
         return 0;
@@ -789,7 +768,7 @@ rcu_torture_writer(void *arg)
                 rcu_stutter_wait("rcu_torture_writer");
         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
         VERBOSE_TOROUT_STRING("rcu_torture_writer task stopping");
-        rcutorture_shutdown_absorb("rcu_torture_writer");
+        torture_shutdown_absorb("rcu_torture_writer");
         while (!kthread_should_stop())
                 schedule_timeout_uninterruptible(1);
         return 0;
@@ -827,7 +806,7 @@ rcu_torture_fakewriter(void *arg)
         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 
         VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task stopping");
-        rcutorture_shutdown_absorb("rcu_torture_fakewriter");
+        torture_shutdown_absorb("rcu_torture_fakewriter");
         while (!kthread_should_stop())
                 schedule_timeout_uninterruptible(1);
         return 0;
@@ -971,7 +950,7 @@ rcu_torture_reader(void *arg)
                 rcu_stutter_wait("rcu_torture_reader");
         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
         VERBOSE_TOROUT_STRING("rcu_torture_reader task stopping");
-        rcutorture_shutdown_absorb("rcu_torture_reader");
+        torture_shutdown_absorb("rcu_torture_reader");
         if (irqreader && cur_ops->irq_capable)
                 del_timer_sync(&t);
         while (!kthread_should_stop())
@@ -1095,7 +1074,7 @@ rcu_torture_stats(void *arg)
         do {
                 schedule_timeout_interruptible(stat_interval * HZ);
                 rcu_torture_stats_print();
-                rcutorture_shutdown_absorb("rcu_torture_stats");
+                torture_shutdown_absorb("rcu_torture_stats");
         } while (!kthread_should_stop());
         VERBOSE_TOROUT_STRING("rcu_torture_stats task stopping");
         return 0;
@@ -1179,7 +1158,7 @@ rcu_torture_shuffle(void *arg)
         do {
                 schedule_timeout_interruptible(shuffle_interval * HZ);
                 rcu_torture_shuffle_tasks();
-                rcutorture_shutdown_absorb("rcu_torture_shuffle");
+                torture_shutdown_absorb("rcu_torture_shuffle");
         } while (!kthread_should_stop());
         VERBOSE_TOROUT_STRING("rcu_torture_shuffle task stopping");
         return 0;
@@ -1198,7 +1177,7 @@ rcu_torture_stutter(void *arg)
                 if (!kthread_should_stop())
                         schedule_timeout_interruptible(stutter * HZ);
                 stutter_pause_test = 0;
-                rcutorture_shutdown_absorb("rcu_torture_stutter");
+                torture_shutdown_absorb("rcu_torture_stutter");
         } while (!kthread_should_stop());
         VERBOSE_TOROUT_STRING("rcu_torture_stutter task stopping");
         return 0;
@@ -1470,7 +1449,7 @@ static int rcu_torture_stall(void *args)
                 rcu_read_unlock();
                 pr_alert("rcu_torture_stall end.\n");
         }
-        rcutorture_shutdown_absorb("rcu_torture_stall");
+        torture_shutdown_absorb("rcu_torture_stall");
         while (!kthread_should_stop())
                 schedule_timeout_interruptible(10 * HZ);
         return 0;
@@ -1534,7 +1513,7 @@ static int rcu_torture_barrier_cbs(void *arg)
                         wake_up(&barrier_wq);
         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
         VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task stopping");
-        rcutorture_shutdown_absorb("rcu_torture_barrier_cbs");
+        torture_shutdown_absorb("rcu_torture_barrier_cbs");
         while (!kthread_should_stop())
                 schedule_timeout_interruptible(1);
         cur_ops->cb_barrier();
@@ -1571,7 +1550,7 @@ static int rcu_torture_barrier(void *arg)
                 schedule_timeout_interruptible(HZ / 10);
         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
         VERBOSE_TOROUT_STRING("rcu_torture_barrier task stopping");
-        rcutorture_shutdown_absorb("rcu_torture_barrier");
+        torture_shutdown_absorb("rcu_torture_barrier");
         while (!kthread_should_stop())
                 schedule_timeout_interruptible(1);
         return 0;