From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9A6B8BA4C for ; Tue, 7 Mar 2023 18:50:06 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C12D6C433D2; Tue, 7 Mar 2023 18:50:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1678215006; bh=2vjIpf5zAHEPy6IFEG8tyq+dyDMx93bJpxc8Bblw5F0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DGahzxdjLG0UFjlxMkna8rjXPpb69y8jSEDSQGDIWm6JZgilqCKLsP7DEghdWaGgX XmKqY4q+S3deZuNM2X1D/cnpdlSXNalDjzB9FyfALbikBscgHNWX6R8fFvGPVqY3Gg raHXI6odRnNZsh9PVNa1im4YdLApnTE75UivVhbs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Boqun Feng , "Paul E. McKenney" , Neeraj Upadhyay , Lai Jiangshan , Frederic Weisbecker , Sasha Levin Subject: [PATCH 5.15 089/567] rcu-tasks: Remove preemption disablement around srcu_read_[un]lock() calls Date: Tue, 7 Mar 2023 17:57:05 +0100 Message-Id: <20230307165909.743714264@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230307165905.838066027@linuxfoundation.org> References: <20230307165905.838066027@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Frederic Weisbecker [ Upstream commit 44757092958bdd749775022f915b7ac974384c2a ] Ever since the following commit: 5a41344a3d83 ("srcu: Simplify __srcu_read_unlock() via this_cpu_dec()") SRCU doesn't rely anymore on preemption to be disabled in order to modify the per-CPU counter. And even then it used to be done from the API itself. Therefore and after checking further, it appears to be safe to remove the preemption disablement around __srcu_read_[un]lock() in exit_tasks_rcu_start() and exit_tasks_rcu_finish() Suggested-by: Boqun Feng Suggested-by: Paul E. McKenney Suggested-by: Neeraj Upadhyay Cc: Lai Jiangshan Signed-off-by: Frederic Weisbecker Signed-off-by: Paul E. McKenney Stable-dep-of: 28319d6dc5e2 ("rcu-tasks: Fix synchronize_rcu_tasks() VS zap_pid_ns_processes()") Signed-off-by: Sasha Levin --- kernel/rcu/tasks.h | 4 ---- 1 file changed, 4 deletions(-) diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index d937bacf27b68..2408ca633872a 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -632,9 +632,7 @@ EXPORT_SYMBOL_GPL(show_rcu_tasks_classic_gp_kthread); */ void exit_tasks_rcu_start(void) __acquires(&tasks_rcu_exit_srcu) { - preempt_disable(); current->rcu_tasks_idx = __srcu_read_lock(&tasks_rcu_exit_srcu); - preempt_enable(); } /* @@ -646,9 +644,7 @@ void exit_tasks_rcu_finish(void) __releases(&tasks_rcu_exit_srcu) { struct task_struct *t = current; - preempt_disable(); __srcu_read_unlock(&tasks_rcu_exit_srcu, t->rcu_tasks_idx); - preempt_enable(); exit_tasks_rcu_finish_trace(t); } -- 2.39.2