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 41cf99930f34..5753f7322262 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 4f284e4f4d8c..42311ee0334f 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 94515ff226fb..3865717df124 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 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);