torture: Check for multiple concurrent torture tests

The torture tests are designed to run in isolation, but do not enforce
this isolation.  This commit therefore checks for concurrent torture
tests, and refuses to start new tests while old tests are running.

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

4 files changed, 16 insertions, 5 deletions

diff --git a/include/linux/torture.h b/include/linux/torture.h
index b2e2b468e511..f998574247fd 100644
--- a/include/linux/torture.h
+++ b/include/linux/torture.h
@@ -81,7 +81,7 @@ void stutter_wait(const char *title);
 int torture_stutter_init(int s);
 
 /* Initialization and cleanup. */
-void torture_init_begin(char *ttype, bool v, int *runnable);
+bool torture_init_begin(char *ttype, bool v, int *runnable);
 void torture_init_end(void);
 bool torture_cleanup(void);
 bool torture_must_stop(void);
diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index 1952466c7db5..dbafeac18e4d 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -355,7 +355,8 @@ static int __init lock_torture_init(void)
                 &lock_busted_ops, &spin_lock_ops, &spin_lock_irq_ops,
         };
 
-        torture_init_begin(torture_type, verbose, &locktorture_runnable);
+        if (!torture_init_begin(torture_type, verbose, &locktorture_runnable))
+                return -EBUSY;
 
         /* Process args and tell the world that the torturer is on the job. */
         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 4b7b97ff1195..7fa34f86e5ba 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1536,7 +1536,8 @@ rcu_torture_init(void)
                 &rcu_ops, &rcu_bh_ops, &rcu_busted_ops, &srcu_ops, &sched_ops,
         };
 
-        torture_init_begin(torture_type, verbose, &rcutorture_runnable);
+        if (!torture_init_begin(torture_type, verbose, &rcutorture_runnable))
+                return -EBUSY;
 
         /* Process args and tell the world that the torturer is on the job. */
         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
diff --git a/kernel/torture.c b/kernel/torture.c
index ae1723a4c751..0ed0b49d2ce1 100644
--- a/kernel/torture.c
+++ b/kernel/torture.c
@@ -599,14 +599,20 @@ static void torture_stutter_cleanup(void)
  * The runnable parameter points to a flag that controls whether or not
  * the test is currently runnable.  If there is no such flag, pass in NULL.
  */
-void __init torture_init_begin(char *ttype, bool v, int *runnable)
+bool __init torture_init_begin(char *ttype, bool v, int *runnable)
 {
         mutex_lock(&fullstop_mutex);
+        if (torture_type != NULL) {
+                pr_alert("torture_init_begin: refusing %s init: %s running",
+                         ttype, torture_type);
+                mutex_unlock(&fullstop_mutex);
+                return false;
+        }
         torture_type = ttype;
         verbose = v;
         torture_runnable = runnable;
         fullstop = FULLSTOP_DONTSTOP;
-
+        return true;
 }
 EXPORT_SYMBOL_GPL(torture_init_begin);
 
@@ -645,6 +651,9 @@ bool torture_cleanup(void)
         torture_shuffle_cleanup();
         torture_stutter_cleanup();
         torture_onoff_cleanup();
+        mutex_lock(&fullstop_mutex);
+        torture_type = NULL;
+        mutex_unlock(&fullstop_mutex);
         return false;
 }
 EXPORT_SYMBOL_GPL(torture_cleanup);