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[59.124.168.89]) by smtp.gmail.com with ESMTPSA id x5-20020a170902ea8500b001d9004b68ddsm4629902plb.252.2024.01.31.22.18.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 31 Jan 2024 22:18:56 -0800 (PST) From: Andy Chiu To: rostedt@goodmis.org, linux-trace-kernel@vger.kernel.org Cc: bristot@kernel.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, Andy Chiu Subject: [v1] trace/osnoise: prevent osnoise hotplog worker running in UNBOUND workqueue Date: Thu, 1 Feb 2024 14:18:45 +0800 Message-ID: <20240201061845.3154289-1-andy.chiu@sifive.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit smp_processor_id() should be called with migration disabled. This mean we may safely call smp_processor_id() in percpu thread. However, this is not the case if the work is (re-)queued into unbound workqueue, during cpu-hotplog. So, detect and return early if this work happens to run on an unbound wq. Signed-off-by: Andy Chiu --- kernel/trace/trace_osnoise.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c index bd0d01d00fb9..cf7f716d3f35 100644 --- a/kernel/trace/trace_osnoise.c +++ b/kernel/trace/trace_osnoise.c @@ -2068,7 +2068,12 @@ static int start_per_cpu_kthreads(void) #ifdef CONFIG_HOTPLUG_CPU static void osnoise_hotplug_workfn(struct work_struct *dummy) { - unsigned int cpu = smp_processor_id(); + unsigned int cpu; + + if (!is_percpu_thread()) + return; + + cpu = smp_processor_id(); mutex_lock(&trace_types_lock); -- 2.43.0