[PATCH 5.4 012/344] rcu/nocb: Fix dump_tree hierarchy print always active

Greg Kroah-Hartman
2020-02-21T08:39:16Z

From: Stefan Reiter <stefan@pimaker.at>

[ Upstream commit 610dea36d3083a977e4f156206cbe1eaa2a532f0 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
kernel/rcu/tree_plugin.h | 22 +++++++++++++++++-----
1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index f849e7429816f..f7118842a2b88 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -2322,6 +2322,8 @@ 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;
@@ -2344,21 +2346,31 @@ 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)");
}

/*
--
2.20.1