From nobody Mon Feb 9 12:01:45 2026 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 89D032BEC59; Mon, 3 Nov 2025 07:19:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762154354; cv=none; b=biAP56elZ+5K1Ms8BF9D3fNp+pb5vNpDGGvRscrvvJbcZ8nXOVi6S3MAMIzS1K3viEIojzmCOmDUXiJo0heu9yNM79O11dRpccZENhux1krtaBGs19vssNWkRIqUrEfJshJHDEhyrX52ovRDmYX0g1oluUKQ0a8SEVaQ1Z7AA1g= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762154354; c=relaxed/simple; bh=bygEsSTdrpTNsepCJbQrl8IEFAGJacekELf8ihO/Yz0=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=MaBPKQT10JxqenaRttLT+mAzOjm0JEMnA1Iw1x6rVNMBfqKLVW/GE6g1/5CH5oDVk/457OlTOy2HMgj5reDPLyiqtz80FpXw7D04gBu5DTuzidTNpBUHTR095LVjuW+bolZwRV5+Mn8Du10E5ByUrzQvl2p38trxE9rm2j2X4ns= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=thHYWLwl; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="thHYWLwl" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 31477C16AAE; Mon, 3 Nov 2025 07:19:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762154354; bh=bygEsSTdrpTNsepCJbQrl8IEFAGJacekELf8ihO/Yz0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=thHYWLwlERq0sMfLXWMZtoaM7fzvVlxq3j/ao6p6PjeWEcCCfhYhO1/tLf8YXHW1E IVWQ7lBA+Q/1fTe+5Rt+5vNNQ6Ncx8EK4cIfnuheI3RNaBUEOEJk2yg5pMacV1gq9l CHjecUVOtgLIPUfc+qIihMz70S1DnPoyQfljIAKq9SKZcAUBsTE9FvVxA5+Cn2y6yF eLOwBQkFl84ZcnozsMM8sVuKHaWog8tKbMihVb7KSeGKimMWiqVCZ4NFXDA+ap9CyI jiTGRDqtSQnPCxXmoI/dHW/ELanlQabdS+y9E+2FvAu15qYC4ygvR7zzlOtiSyEwAu h9GpcUSA3CYOQ== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id B6E60CE16F7; Sun, 2 Nov 2025 15:07:01 -0800 (PST) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@meta.com, rostedt@goodmis.org, "Paul E. McKenney" , Frederic Weisbecker , Andrii Nakryiko , Alexei Starovoitov , Peter Zijlstra , bpf@vger.kernel.org Subject: [PATCH 2/9] context_tracking: Remove rcu_task_trace_heavyweight_{enter,exit}() Date: Sun, 2 Nov 2025 15:06:52 -0800 Message-Id: <20251102230659.3906740-2-paulmck@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Because SRCU-fast does not use IPIs for its grace periods, there is no need for real-time workloads to switch to an IPI-free mode, and there is in turn no need for either rcu_task_trace_heavyweight_enter() or rcu_task_trace_heavyweight_exit(). This commit therefore removes them. Signed-off-by: Paul E. McKenney Cc: Frederic Weisbecker Cc: Andrii Nakryiko Cc: Alexei Starovoitov Cc: Peter Zijlstra Cc: --- kernel/context_tracking.c | 20 -------------------- 1 file changed, 20 deletions(-) diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index fb5be6e9b423..a743e7ffa6c0 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -54,24 +54,6 @@ static __always_inline void rcu_task_enter(void) #endif /* #if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL) */ } =20 -/* Turn on heavyweight RCU tasks trace readers on kernel exit. */ -static __always_inline void rcu_task_trace_heavyweight_enter(void) -{ -#ifdef CONFIG_TASKS_TRACE_RCU - if (IS_ENABLED(CONFIG_TASKS_TRACE_RCU_READ_MB)) - current->trc_reader_special.b.need_mb =3D true; -#endif /* #ifdef CONFIG_TASKS_TRACE_RCU */ -} - -/* Turn off heavyweight RCU tasks trace readers on kernel entry. */ -static __always_inline void rcu_task_trace_heavyweight_exit(void) -{ -#ifdef CONFIG_TASKS_TRACE_RCU - if (IS_ENABLED(CONFIG_TASKS_TRACE_RCU_READ_MB)) - current->trc_reader_special.b.need_mb =3D false; -#endif /* #ifdef CONFIG_TASKS_TRACE_RCU */ -} - /* * Record entry into an extended quiescent state. This is only to be * called when not already in an extended quiescent state, that is, @@ -85,7 +67,6 @@ static noinstr void ct_kernel_exit_state(int offset) * critical sections, and we also must force ordering with the * next idle sojourn. */ - rcu_task_trace_heavyweight_enter(); // Before CT state update! // RCU is still watching. Better not be in extended quiescent state! WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !rcu_is_watching_curr_cp= u()); (void)ct_state_inc(offset); @@ -108,7 +89,6 @@ static noinstr void ct_kernel_enter_state(int offset) */ seq =3D ct_state_inc(offset); // RCU is now watching. Better not be in an extended quiescent state! - rcu_task_trace_heavyweight_exit(); // After CT state update! WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !(seq & CT_RCU_WATCHING)= ); } =20 --=20 2.40.1