linux-kernel - [PATCH rcu 06/11] rcu: Print number of online CPUs in RCU CPU stall-warning messages

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20220418225359.3945217-6-paulmck@kernel.org>
Date:   Mon, 18 Apr 2022 15:53:54 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     rcu@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, kernel-team@...com,
        rostedt@...dmis.org, "Paul E. McKenney" <paulmck@...nel.org>
Subject: [PATCH rcu 06/11] rcu: Print number of online CPUs in RCU CPU stall-warning messages

RCU's synchronous grace periods act quite differently when there is
only one online CPU, especially in the no-op case in kernels built with
CONFIG_PREEMPTION=n.  This change in behavior can be important debugging
information, so this commit adds the number of online CPUs to the RCU
CPU stall warning messages.

Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
---
 kernel/rcu/tree_stall.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index 0c5d8516516a..268dd79c58e7 100644
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -565,9 +565,9 @@ static void print_other_cpu_stall(unsigned long gp_seq, unsigned long gps)
 
 	for_each_possible_cpu(cpu)
 		totqlen += rcu_get_n_cbs_cpu(cpu);
-	pr_cont("\t(detected by %d, t=%ld jiffies, g=%ld, q=%lu)\n",
+	pr_cont("\t(detected by %d, t=%ld jiffies, g=%ld, q=%lu ncpus=%d)\n",
 	       smp_processor_id(), (long)(jiffies - gps),
-	       (long)rcu_seq_current(&rcu_state.gp_seq), totqlen);
+	       (long)rcu_seq_current(&rcu_state.gp_seq), totqlen, rcu_state.n_online_cpus);
 	if (ndetected) {
 		rcu_dump_cpu_stacks();
 
@@ -626,9 +626,9 @@ static void print_cpu_stall(unsigned long gps)
 	raw_spin_unlock_irqrestore_rcu_node(rdp->mynode, flags);
 	for_each_possible_cpu(cpu)
 		totqlen += rcu_get_n_cbs_cpu(cpu);
-	pr_cont("\t(t=%lu jiffies g=%ld q=%lu)\n",
+	pr_cont("\t(t=%lu jiffies g=%ld q=%lu ncpus=%d)\n",
 		jiffies - gps,
-		(long)rcu_seq_current(&rcu_state.gp_seq), totqlen);
+		(long)rcu_seq_current(&rcu_state.gp_seq), totqlen, rcu_state.n_online_cpus);
 
 	rcu_check_gp_kthread_expired_fqs_timer();
 	rcu_check_gp_kthread_starvation();
-- 
2.31.1.189.g2e36527f23