tracing/hwlat: Fix a race during cpuhp processing
commit 2a13ca2e8abb12ee43ada8a107dadca83f140937 upstream. The cpuhp online/offline processing race also exists in percpu-mode hwlat tracer in theory, apply the fix too. That is: T1 | T2 [CPUHP_ONLINE] | cpu_device_down() hwlat_hotplug_workfn() | | cpus_write_lock() | takedown_cpu(1) | cpus_write_unlock() [CPUHP_OFFLINE] | cpus_read_lock() | start_kthread(1) | cpus_read_unlock() | Cc: stable@vger.kernel.org Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Link: https://lore.kernel.org/20240924094515.3561410-5-liwei391@huawei.com Fixes: ba998f7d9531 ("trace/hwlat: Support hotplug operations") Signed-off-by: Wei Li <liwei391@huawei.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -520,6 +520,8 @@ static void hwlat_hotplug_workfn(struct work_struct *dummy)
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if (!hwlat_busy || hwlat_data.thread_mode != MODE_PER_CPU)
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if (!hwlat_busy || hwlat_data.thread_mode != MODE_PER_CPU)
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goto out_unlock;
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goto out_unlock;
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if (!cpu_online(cpu))
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goto out_unlock;
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if (!cpumask_test_cpu(cpu, tr->tracing_cpumask))
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if (!cpumask_test_cpu(cpu, tr->tracing_cpumask))
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goto out_unlock;
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goto out_unlock;
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