rcu: Add diagnostics for rcutorture writer stall warning

This commit adds any in-the-future ->gp_seq_needed fields to the
diagnostics for an rcutorture writer stall warning message.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 7746fe1ee3fc..4915525559ac 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -606,11 +606,32 @@ EXPORT_SYMBOL_GPL(rcu_sched_force_quiescent_state);
  */
 void show_rcu_gp_kthreads(void)
 {
+        int cpu;
+        struct rcu_data *rdp;
+        struct rcu_node *rnp;
         struct rcu_state *rsp;
 
         for_each_rcu_flavor(rsp) {
                 pr_info("%s: wait state: %d ->state: %#lx\n",
                         rsp->name, rsp->gp_state, rsp->gp_kthread->state);
+                rcu_for_each_node_breadth_first(rsp, rnp) {
+                        if (ULONG_CMP_GE(rsp->gp_seq, rnp->gp_seq_needed))
+                                continue;
+                        pr_info("\trcu_node %d:%d ->gp_seq %lu ->gp_seq_needed %lu\n",
+                                rnp->grplo, rnp->grphi, rnp->gp_seq,
+                                rnp->gp_seq_needed);
+                        if (!rcu_is_leaf_node(rnp))
+                                continue;
+                        for_each_leaf_node_possible_cpu(rnp, cpu) {
+                                rdp = per_cpu_ptr(rsp->rda, cpu);
+                                if (rdp->gpwrap ||
+                                    ULONG_CMP_GE(rsp->gp_seq,
+                                                 rdp->gp_seq_needed))
+                                        continue;
+                                pr_info("\tcpu %d ->gp_seq_needed %lu\n",
+                                        cpu, rdp->gp_seq_needed);
+                        }
+                }
                 /* sched_show_task(rsp->gp_kthread); */
         }
 }