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[185.121.47.193]) by smtp.gmail.com with ESMTPSA id t18-20020a2e9d12000000b002e29c50c4dcsm1335473lji.27.2024.05.07.02.35.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 07 May 2024 02:35:48 -0700 (PDT) From: "Uladzislau Rezki (Sony)" To: "Paul E . McKenney" Cc: RCU , Neeraj upadhyay , Boqun Feng , Hillf Danton , Joel Fernandes , LKML , Uladzislau Rezki , Oleksiy Avramchenko , Frederic Weisbecker , Steven Rostedt , Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Ankur Arora , Thomas Gleixner , linux-trace-kernel@vger.kernel.org Subject: [PATCH 16/48] ftrace: Choose RCU Tasks based on TASKS_RCU rather than PREEMPTION Date: Tue, 7 May 2024 11:34:58 +0200 Message-Id: <20240507093530.3043-17-urezki@gmail.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240507093530.3043-1-urezki@gmail.com> References: <20240507093530.3043-1-urezki@gmail.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: "Paul E. McKenney" The advent of CONFIG_PREEMPT_AUTO, AKA lazy preemption, will mean that even kernels built with CONFIG_PREEMPT_NONE or CONFIG_PREEMPT_VOLUNTARY might see the occasional preemption, and that this preemption just might happen within a trampoline. Therefore, update ftrace_shutdown() to invoke synchronize_rcu_tasks() based on CONFIG_TASKS_RCU instead of CONFIG_PREEMPTION. [ paulmck: Apply Steven Rostedt feedback. ] Signed-off-by: Paul E. McKenney Cc: Steven Rostedt Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Ankur Arora Cc: Thomas Gleixner Cc: Signed-off-by: Uladzislau Rezki (Sony) --- kernel/trace/ftrace.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index da1710499698..6c96b30f3d63 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -3157,8 +3157,7 @@ int ftrace_shutdown(struct ftrace_ops *ops, int command) * synchronize_rcu_tasks() will wait for those tasks to * execute and either schedule voluntarily or enter user space. */ - if (IS_ENABLED(CONFIG_PREEMPTION)) - synchronize_rcu_tasks(); + synchronize_rcu_tasks(); ftrace_trampoline_free(ops); }