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author | Paul E. McKenney <paulmck@kernel.org> | 2024-03-07 20:14:55 -0800 |
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committer | Uladzislau Rezki (Sony) <urezki@gmail.com> | 2024-04-15 16:48:26 +0200 |
commit | 09e077cf22c4302ab4ca7932f56c5a8b20c9e32b (patch) | |
tree | a3f3e21b7f1c16499eca1e002cd829963f4866bd /kernel/rcu/tree_stall.h | |
parent | a542d116bab28b4bcade2f41488f4617373c620f (diff) | |
download | lwn-09e077cf22c4302ab4ca7932f56c5a8b20c9e32b.tar.gz lwn-09e077cf22c4302ab4ca7932f56c5a8b20c9e32b.zip |
rcu: Mark loads from rcu_state.n_online_cpus
The rcu_state.n_online_cpus value is only ever updated by CPU-hotplug
operations, which are serialized. However, this value is read locklessly.
This commit therefore marks those reads. While in the area, it also
adds ASSERT_EXCLUSIVE_WRITER() calls just in case parallel CPU hotplug
becomes a thing.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Diffstat (limited to 'kernel/rcu/tree_stall.h')
-rw-r--r-- | kernel/rcu/tree_stall.h | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index 62b2c4858028..8a2edf6a1ef5 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -628,7 +628,8 @@ static void print_other_cpu_stall(unsigned long gp_seq, unsigned long gps) totqlen += rcu_get_n_cbs_cpu(cpu); pr_err("\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, rcu_state.n_online_cpus); + (long)rcu_seq_current(&rcu_state.gp_seq), totqlen, + data_race(rcu_state.n_online_cpus)); // Diagnostic read if (ndetected) { rcu_dump_cpu_stacks(); @@ -689,7 +690,8 @@ static void print_cpu_stall(unsigned long gps) totqlen += rcu_get_n_cbs_cpu(cpu); pr_err("\t(t=%lu jiffies g=%ld q=%lu ncpus=%d)\n", jiffies - gps, - (long)rcu_seq_current(&rcu_state.gp_seq), totqlen, rcu_state.n_online_cpus); + (long)rcu_seq_current(&rcu_state.gp_seq), totqlen, + data_race(rcu_state.n_online_cpus)); // Diagnostic read rcu_check_gp_kthread_expired_fqs_timer(); rcu_check_gp_kthread_starvation(); |