rcu: Add online/offline info to stall warning message

This commit makes the RCU CPU stall warning message print online/offline
indications immediately after a hyphen following the CPU number.  A "O"
indicates that the global CPU-hotplug system believes that the CPU is
online, a "o" that RCU perceived the CPU to be online at the beginning
of the current expedited grace period, and an "N" that RCU currently
believes that it will perceive the CPU as being online at the beginning
of the next expedited grace period, with "." otherwise for all three
indications.  So for CPU 10, you would normally see "10-OoN:" indicating
that everything believes that the CPU is online.

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

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 06116ae6dfd7237ea189c3d5ec00de5acb141287..57ed9c13ae5a2372b4e7aedcf70daae2522993c3 100644 (file)
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1702,8 +1702,12 @@ static void print_cpu_stall_info(struct rcu_state *rsp, int cpu)
                ticks_value = rsp->gpnum - rdp->gpnum;
        }
        print_cpu_stall_fast_no_hz(fast_no_hz, cpu);
-       pr_err("\t%d: (%lu %s) idle=%03x/%llx/%d softirq=%u/%u fqs=%ld %s\n",
-              cpu, ticks_value, ticks_title,
+       pr_err("\t%d-%c%c%c: (%lu %s) idle=%03x/%llx/%d softirq=%u/%u fqs=%ld %s\n",
+              cpu,
+              "O."[!!cpu_online(cpu)],
+              "o."[!!(rdp->grpmask & rdp->mynode->qsmaskinit)],
+              "N."[!!(rdp->grpmask & rdp->mynode->qsmaskinitnext)],
+              ticks_value, ticks_title,
               atomic_read(&rdtp->dynticks) & 0xfff,
               rdtp->dynticks_nesting, rdtp->dynticks_nmi_nesting,
               rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu),