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>

6 files changed, 52 insertions, 11 deletions

diff --git a/include/linux/srcuclassic.h b/include/linux/srcuclassic.h
index 41cf999..5753f73 100644
--- a/include/linux/srcuclassic.h
+++ b/include/linux/srcuclassic.h
@@ -98,4 +98,18 @@ void synchronize_srcu_expedited(struct srcu_struct *sp);
 void srcu_barrier(struct srcu_struct *sp);
 unsigned long srcu_batches_completed(struct srcu_struct *sp);
 
+static inline 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 = sp->completed;
+	*gpnum = *completed;
+	if (sp->batch_queue.head || sp->batch_check0.head || sp->batch_check0.head)
+		(*gpnum)++;
+}
+
 #endif
diff --git a/include/linux/srcutiny.h b/include/linux/srcutiny.h
index 4f284e4..42311ee 100644
--- a/include/linux/srcutiny.h
+++ b/include/linux/srcutiny.h
@@ -78,4 +78,16 @@ static inline unsigned long srcu_batches_completed(struct srcu_struct *sp)
 	return 0;
 }
 
+static inline 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 = sp->srcu_gp_seq;
+	*gpnum = *completed;
+}
+
 #endif
diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h
index 94515ff..3865717 100644
--- a/include/linux/srcutree.h
+++ b/include/linux/srcutree.h
@@ -140,4 +140,8 @@ void synchronize_srcu_expedited(struct srcu_struct *sp);
 void srcu_barrier(struct srcu_struct *sp);
 unsigned long srcu_batches_completed(struct srcu_struct *sp);
 
+void srcutorture_get_gp_data(enum rcutorture_type test_type,
+			     struct srcu_struct *sp, int *flags,
+			     unsigned long *gpnum, unsigned long *completed);
+
 #endif
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index e9d4527..ae6e574 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 1c2c100..72b6cce 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 23aa025..91fff49 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);