From nobody Fri Dec 19 06:30:54 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 D451812880A; Wed, 15 May 2024 12:53:47 +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=1715777627; cv=none; b=r1tF+6t3Qkg8Ju179BjxMSNbfcwQuDy42L6SOHn4cPy2TQogV8PLF40lk7812NpgZpUrhLVCME2EwaNhBcaKgC1OVFV4cUZMBg20QaUQFN37P8ojupw2Xd9FccvWRqw/7qwdjfV6SAG9wHwOm9Va83WKjlaCgMDJ0J7NDaCepPc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715777627; c=relaxed/simple; bh=Cwf7KVnfd1lPdYZIzVZjhOBDZCNVDm3+eiHPehIQsUM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MD0sMQXzC04gbrhwwLAPmIG4+3JCcwaJadff0ipzVaaN0jeHQCiHtgJ2Uxyo7CA23FikpQszrzkKR4r1J12LsXrAKIwiYRORHbSl/rXCKwCFZ3rdi4vio/dlGpf3GSYCKwJPw3vrsIFE0+/ggdNeo2ovsQaEIquIeUyGSqAlEPM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Jk/IArrO; 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="Jk/IArrO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7A9D6C116B1; Wed, 15 May 2024 12:53:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1715777627; bh=Cwf7KVnfd1lPdYZIzVZjhOBDZCNVDm3+eiHPehIQsUM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Jk/IArrO6/Ocivft4HDWBiiKfGZW17EWtQmnaEY6IvqGqfzXtA67ivHh4gIxMnIu9 rmeRvHRY20SaosNvaMYQK2TDaKrwoHmbRw3veWnYz4JVRJzSWU5XBlxpN52ALGZXG8 ySlFelKvcW5WE4wYzANVet9cLfTwNb/H58xl3TFMkMo6/bqfN3+UCfauQT2gBgUT8G NhJQtR3S9Q6+b5tGKHulGmML5Fcuc1F0zydSyayp71ZEgmr8KvHwh8Ve/En0gtilYT 4zC/NpYuWhh54xMrmEyGqRfIFbjxf94J0xM1Q/a0LKcvsvrVHWmzqPYEv2LD/DCNQF Moq/KJ+/cwo/g== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Valentin Schneider , "Paul E . McKenney" , Boqun Feng , Joel Fernandes , Neeraj Upadhyay , Uladzislau Rezki , Zqiang , rcu Subject: [PATCH 4/6] rcu: Remove full memory barrier on boot time eqs sanity check Date: Wed, 15 May 2024 14:53:30 +0200 Message-ID: <20240515125332.9306-5-frederic@kernel.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240515125332.9306-1-frederic@kernel.org> References: <20240515125332.9306-1-frederic@kernel.org> 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" When the boot CPU initializes the per-CPU data on behalf of all possible CPUs, a sanity check is performed on each of them to make sure none is initialized in an extended quiescent state. This check involves a full memory barrier which is useless at this early boot stage. Do a plain access instead. Signed-off-by: Frederic Weisbecker Reviewed-by: Valentin Schneider --- kernel/rcu/tree.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index f5354de5644b..02f6f3483482 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -4812,7 +4812,7 @@ rcu_boot_init_percpu_data(int cpu) rdp->grpmask =3D leaf_node_cpu_bit(rdp->mynode, cpu); INIT_WORK(&rdp->strict_work, strict_work_handler); WARN_ON_ONCE(ct->dynticks_nesting !=3D 1); - WARN_ON_ONCE(rcu_dynticks_in_eqs(rcu_dynticks_snap(cpu))); + WARN_ON_ONCE(rcu_dynticks_in_eqs(ct_dynticks_cpu(cpu))); rdp->barrier_seq_snap =3D rcu_state.barrier_sequence; rdp->rcu_ofl_gp_seq =3D rcu_state.gp_seq; rdp->rcu_ofl_gp_state =3D RCU_GP_CLEANED; --=20 2.44.0