rcu/nocb: Fix dump_tree hierarchy print always active

Commit 18cd8c93e69e ("rcu/nocb: Print gp/cb kthread hierarchy if
dump_tree") added print statements to rcu_organize_nocb_kthreads for
debugging, but incorrectly guarded them, causing the function to always
spew out its message.

This patch fixes it by guarding both pr_alert statements with dump_tree,
while also changing the second pr_alert to a pr_cont, to print the
hierarchy in a single line (assuming that's how it was supposed to
work).

Fixes: 18cd8c93e69e ("rcu/nocb: Print gp/cb kthread hierarchy if dump_tree")
Signed-off-by: Stefan Reiter <stefan@pimaker.at>
[ paulmck: Make single-nocbs-CPU GP kthreads look less erroneous. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index fa08d55..758bfe1 100644 (file)
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -2321,6 +2321,8 @@ static void __init rcu_organize_nocb_kthreads(void)
 {
        int cpu;
        bool firsttime = true;
+       bool gotnocbs = false;
+       bool gotnocbscbs = true;
        int ls = rcu_nocb_gp_stride;
        int nl = 0;  /* Next GP kthread. */
        struct rcu_data *rdp;
@@ -2343,21 +2345,31 @@ static void __init rcu_organize_nocb_kthreads(void)
                rdp = per_cpu_ptr(&rcu_data, cpu);
                if (rdp->cpu >= nl) {
                        /* New GP kthread, set up for CBs & next GP. */
+                       gotnocbs = true;
                        nl = DIV_ROUND_UP(rdp->cpu + 1, ls) * ls;
                        rdp->nocb_gp_rdp = rdp;
                        rdp_gp = rdp;
-                       if (!firsttime && dump_tree)
-                               pr_cont("\n");
-                       firsttime = false;
-                       pr_alert("%s: No-CB GP kthread CPU %d:", __func__, cpu);
+                       if (dump_tree) {
+                               if (!firsttime)
+                                       pr_cont("%s\n", gotnocbscbs
+                                                       ? "" : " (self only)");
+                               gotnocbscbs = false;
+                               firsttime = false;
+                               pr_alert("%s: No-CB GP kthread CPU %d:",
+                                        __func__, cpu);
+                       }
                } else {
                        /* Another CB kthread, link to previous GP kthread. */
+                       gotnocbscbs = true;
                        rdp->nocb_gp_rdp = rdp_gp;
                        rdp_prev->nocb_next_cb_rdp = rdp;
-                       pr_alert(" %d", cpu);
+                       if (dump_tree)
+                               pr_cont(" %d", cpu);
                }
                rdp_prev = rdp;
        }
+       if (gotnocbs && dump_tree)
+               pr_cont("%s\n", gotnocbscbs ? "" : " (self only)");
 }
 
 /*