srcu: Make rcutorture writer stalls print SRCU GP state

In the past, SRCU was simple enough that there was little point in
making the rcutorture writer stall messages print the SRCU grace-period
number state.  With the advent of Tree SRCU, this has changed.  This
commit therefore makes Classic, Tiny, and Tree SRCU report this state
to rcutorture as needed.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Mike Galbraith <efault@gmx.de>

3 files changed, 22 insertions, 11 deletions

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index e9d4527cdd43..ae6e574d4cf5 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1360,12 +1360,14 @@ rcu_torture_stats_print(void)
 		cur_ops->stats();
 	if (rtcv_snap == rcu_torture_current_version &&
 	    rcu_torture_current != NULL) {
-		int __maybe_unused flags;
-		unsigned long __maybe_unused gpnum;
-		unsigned long __maybe_unused completed;
+		int __maybe_unused flags = 0;
+		unsigned long __maybe_unused gpnum = 0;
+		unsigned long __maybe_unused completed = 0;
 
 		rcutorture_get_gp_data(cur_ops->ttype,
 				       &flags, &gpnum, &completed);
+		srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp,
+					&flags, &gpnum, &completed);
 		wtp = READ_ONCE(writer_task);
 		pr_alert("??? Writer stall state %s(%d) g%lu c%lu f%#x ->state %#lx\n",
 			 rcu_torture_writer_state_getname(),
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index 1c2c1004b3b1..72b6cce5f591 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -1011,3 +1011,16 @@ void process_srcu(struct work_struct *work)
 	srcu_reschedule(sp, atomic_read(&sp->srcu_exp_cnt) ? 0 : SRCU_INTERVAL);
 }
 EXPORT_SYMBOL_GPL(process_srcu);
+
+void srcutorture_get_gp_data(enum rcutorture_type test_type,
+					   struct srcu_struct *sp, int *flags,
+					   unsigned long *gpnum,
+					   unsigned long *completed)
+{
+	if (test_type != SRCU_FLAVOR)
+		return;
+	*flags = 0;
+	*completed = rcu_seq_ctr(sp->srcu_gp_seq);
+	*gpnum = rcu_seq_ctr(sp->srcu_gp_seq_needed);
+}
+EXPORT_SYMBOL_GPL(srcutorture_get_gp_data);
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 23aa02587d0f..91fff49d5869 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -704,15 +704,11 @@ void rcutorture_get_gp_data(enum rcutorture_type test_type, int *flags,
 	default:
 		break;
 	}
-	if (rsp != NULL) {
-		*flags = READ_ONCE(rsp->gp_flags);
-		*gpnum = READ_ONCE(rsp->gpnum);
-		*completed = READ_ONCE(rsp->completed);
+	if (rsp == NULL)
 		return;
-	}
-	*flags = 0;
-	*gpnum = 0;
-	*completed = 0;
+	*flags = READ_ONCE(rsp->gp_flags);
+	*gpnum = READ_ONCE(rsp->gpnum);
+	*completed = READ_ONCE(rsp->completed);
 }
 EXPORT_SYMBOL_GPL(rcutorture_get_gp_data);