From: Daniel Bristot de Oliveira <bristot@redhat.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Phil Auld <pauld@redhat.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Kate Carcia <kcarcia@redhat.com>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
Jonathan Corbet <corbet@lwn.net>, Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Alexandre Chartre <alexandre.chartre@oracle.com>,
Clark Willaims <williams@redhat.com>,
John Kacur <jkacur@redhat.com>,
Juri Lelli <juri.lelli@redhat.com>,
Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [PATCH V5 11/14] trace/hwlat: Protect kdata->kthread with get/put_online_cpus
Date: Tue, 22 Jun 2021 16:42:29 +0200 [thread overview]
Message-ID: <8bdb2a56f46abfd301d6fffbf43448380c09a6f5.1624372313.git.bristot@redhat.com> (raw)
In-Reply-To: <cover.1624372313.git.bristot@redhat.com>
In preparation to the hotplug support, protect kdata->kthread
with get/put_online_cpus() to avoid concurrency with hotplug
operations.
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Alexandre Chartre <alexandre.chartre@oracle.com>
Cc: Clark Willaims <williams@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
---
kernel/trace/trace_hwlat.c | 19 +++++++++++++------
1 file changed, 13 insertions(+), 6 deletions(-)
diff --git a/kernel/trace/trace_hwlat.c b/kernel/trace/trace_hwlat.c
index 8756ab24c132..dc30b8a9bd5f 100644
--- a/kernel/trace/trace_hwlat.c
+++ b/kernel/trace/trace_hwlat.c
@@ -396,13 +396,19 @@ static int kthread_fn(void *data)
static void stop_single_kthread(void)
{
struct hwlat_kthread_data *kdata = get_cpu_data();
- struct task_struct *kthread = kdata->kthread;
+ struct task_struct *kthread;
+
+ get_online_cpus();
+ kthread = kdata->kthread;
if (!kthread)
- return;
+ goto out_put_cpus;
kthread_stop(kthread);
kdata->kthread = NULL;
+
+out_put_cpus:
+ put_online_cpus();
}
@@ -419,20 +425,19 @@ static int start_single_kthread(struct trace_array *tr)
struct task_struct *kthread;
int next_cpu;
+ get_online_cpus();
if (kdata->kthread)
- return 0;
+ goto out_put_cpus;
kthread = kthread_create(kthread_fn, NULL, "hwlatd");
if (IS_ERR(kthread)) {
pr_err(BANNER "could not start sampling thread\n");
+ put_online_cpus();
return -ENOMEM;
}
-
/* Just pick the first CPU on first iteration */
- get_online_cpus();
cpumask_and(current_mask, cpu_online_mask, tr->tracing_cpumask);
- put_online_cpus();
if (hwlat_data.thread_mode == MODE_ROUND_ROBIN) {
next_cpu = cpumask_first(current_mask);
@@ -446,6 +451,8 @@ static int start_single_kthread(struct trace_array *tr)
kdata->kthread = kthread;
wake_up_process(kthread);
+out_put_cpus:
+ put_online_cpus();
return 0;
}
--
2.31.1
next prev parent reply other threads:[~2021-06-22 14:44 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-22 14:42 [PATCH V5 00/14] hwlat improvements and osnoise/timerlat tracers Daniel Bristot de Oliveira
2021-06-22 14:42 ` [PATCH V5 01/14] trace/hwlat: Fix Clark's email Daniel Bristot de Oliveira
2021-06-22 14:42 ` [PATCH V5 02/14] trace/hwlat: Implement the mode config option Daniel Bristot de Oliveira
2021-06-22 14:42 ` [PATCH V5 03/14] trace/hwlat: Switch disable_migrate to mode none Daniel Bristot de Oliveira
2021-06-22 14:42 ` [PATCH V5 04/14] trace/hwlat: Implement the per-cpu mode Daniel Bristot de Oliveira
2021-06-22 14:42 ` [PATCH V5 05/14] trace: Add a generic function to read/write u64 values from tracefs Daniel Bristot de Oliveira
2021-06-22 14:42 ` [PATCH V5 06/14] trace/hwlat: Use trace_min_max_param for width and window params Daniel Bristot de Oliveira
2021-06-22 14:42 ` [PATCH V5 07/14] trace/hwlat: Remove printk from sampling loop Daniel Bristot de Oliveira
2021-06-22 14:42 ` [PATCH V5 08/14] trace: Add __print_ns_to_secs() and __print_ns_without_secs() helpers Daniel Bristot de Oliveira
2021-06-22 14:42 ` [PATCH V5 09/14] trace: Add osnoise tracer Daniel Bristot de Oliveira
2021-06-22 14:42 ` [PATCH V5 10/14] trace: Add timerlat tracer Daniel Bristot de Oliveira
2021-06-22 14:42 ` Daniel Bristot de Oliveira [this message]
2021-06-22 14:42 ` [PATCH V5 12/14] trace: Protect tr->tracing_cpumask with get/put_online_cpus Daniel Bristot de Oliveira
2021-06-24 21:39 ` Steven Rostedt
2021-06-25 4:34 ` Daniel Bristot de Oliveira
2021-06-25 9:27 ` Peter Zijlstra
2021-06-25 9:31 ` Sebastian Andrzej Siewior
2021-06-22 14:42 ` [PATCH V5 13/14] trace/hwlat: Support hotplug operations Daniel Bristot de Oliveira
2021-06-22 14:42 ` [PATCH V5 14/14] trace/osnoise: " Daniel Bristot de Oliveira
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