From nobody Wed Oct 1 21:35:22 2025 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 5D0232550D4; Wed, 1 Oct 2025 14:48:37 +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=1759330117; cv=none; b=ezpM+OzqX+Qv/Kwz4NHzis3SRaRVUovudGP/grPxE85mDCUQi/KtlhBVNdd2v8tvy8vkQsD86hRr4QfFAKJox7s6DR31rLsyBqMDFbUfNOSf9Fi8hc9hPMUti+LKcg9yegeSGsMiarXXWvbsUPLpJgljhZ020A0ACQ90gAebPtU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759330117; c=relaxed/simple; bh=gORzw/K5miRE/rNReHV1tjj65oo9eOSliJxhQHUaXtc=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=m8ogYNaBFCWfeq8RdEdTVEKjsFXgO5HfK+B8HdnHJcTwIrEY7LzXkW/DteGC+eq89/UdpqwMjLom9VqLMw+YJeiY8DpuAq8jJmZY2aWUIWwn9qGghsR4HkW7igb3INlvRVl37O4Ycs2E17+GPK5UGTgMvYeIu7Otg9me2ixoAXw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=TAjk6kgo; 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="TAjk6kgo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CBA60C4CEF1; Wed, 1 Oct 2025 14:48:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1759330117; bh=gORzw/K5miRE/rNReHV1tjj65oo9eOSliJxhQHUaXtc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TAjk6kgoN0vOc2F0MkIZtzNr7hH4kTxjfAyN/4fVnEOvFSXXNfHvbBtn1rXkw5DjZ YXNsEI/ph4XsHnjkmHjPryT3fASSsNefGPzmPJ1EHwqrWrpm82yhlUB8lKMGlZIIXN kQsF8svNELpG7AUexB8v1tTConjdElRG9zjdyJ3j7TUZ7YhUK1gVKh0mFS+qYoqXU6 lEJM58sgpLQZBoEs3/kaZwYHDbCFMguvdHZ2LCeVAnApaW1uC4U32eJRzcXGbHv6bO dL2iI7gfjXo4EFMMfaSkiYZEiAj0ozo/qDJOeooxunJ9bzaexSDHVxR+867XQC1p1R zALpxcOb3+CNQ== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 677A3CE10DB; Wed, 1 Oct 2025 07:48:34 -0700 (PDT) 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 v2 03/21] context_tracking: Remove rcu_task_trace_heavyweight_{enter,exit}() Date: Wed, 1 Oct 2025 07:48:14 -0700 Message-Id: <20251001144832.631770-3-paulmck@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <7fa58961-2dce-4e08-8174-1d1cc592210f@paulmck-laptop> References: <7fa58961-2dce-4e08-8174-1d1cc592210f@paulmck-laptop> 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 fb5be6e9b423f2..a743e7ffa6c00f 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