From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 092C13314DE; Sat, 19 Sep 2026 00:35:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789778153; cv=none; b=MdLKn2NV5Ep7ZBUAtJoqwAZvCtsXHkdvF3SgU+Wf3jp4zM7Q0BoP/188K3GCWFpn0Bq5OZu7nUCtlFn61Ly6ImJnyvo1ZufN5rPmpmQLT7YZ4f+RyxBm/iQYYWeG3pD9J/vRVETe/6xZvVmN+DajnORndJt0vlUdzmpwrPpRK5Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789778153; c=relaxed/simple; bh=aJYWfRSy/NUVtGdVhme/KTv53wTCn+one3vRc4xjogg=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=ndjQ3Y1bMtCNLGGXSglu+tBlE6+CVWrNKvULumde/k7MjK9GcAMnrBzUpPAeaP7tPdBLt2recqS6xGkmFe65TJptlzmosv2FPdtgqczixqapOMSC1lumhfkkE9sx+3wZ/AP22OcTAon82D3C7NjVacMFyaZVtEVBCg0t7CFXNfs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bgraV3mj; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bgraV3mj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 40C701F008BF; Sat, 19 Sep 2026 00:35:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789778123; bh=xIPHqN/G+Mi8IG9vs/cZ+W8abYmjux4zldBuPhBLEgc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=bgraV3mjWelfEiA+0nwhbGQH0bixwU9fKbXGE2ckuXhDm18q1FVt4jywLgdD9ucns N8GmI2PKf45VUeths8SbxyUiL3qE/fDsN32RxXE+cD5+OQbBeYbyfwG4EfDuelpLrO 5TKww4ECIfmuklDMxLn37gqfRdv1dAd02RyfnQWawcFTL5Kt1BaoqkLf3kjlVEBHeM p4blgH1HNxWQlnSJ4muNANaR5taMVGAwQppqHRP1Bix838SGHCtuGr6JuL3qohP2gF i++H9eFPQ44YuMckVNdsdmetcFqIhqYdUtLKum0OUMSmsfGcF3VcL/QiFWl7z2CGcS d6IH4QTKcG88w== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id B5489CE1978; Fri, 18 Sep 2026 17:35:22 -0700 (PDT) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@meta.com, rostedt@goodmis.org, Kunwu Chan , "Paul E . McKenney" Subject: [PATCH 14/19] srcutree: Skip callback scheduling for atomic SRCU grace periods Date: Fri, 18 Sep 2026 17:35:16 -0700 Message-Id: <20260919003521.3134552-14-paulmck@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <13d6be93-8d9d-47a2-beb0-99c8a90938d4@paulmck-laptop> References: <13d6be93-8d9d-47a2-beb0-99c8a90938d4@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: 8bit From: Kunwu Chan call_srcu() is forbidden on atomic srcu_struct, so srcu_gp_end() never has callbacks to invoke for them. Yet it schedules callback invocation, which for atomic SRCU's SRCU_SIZE_SMALL state arms the boot CPU's ->delay_work timer every grace period, only for srcu_invoke_callbacks() to find nothing to do. Skip this for atomic SRCU. Signed-off-by: Kunwu Chan Signed-off-by: Paul E. McKenney --- kernel/rcu/srcutree.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 93b8d1088abe..0954486880c7 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -1016,10 +1016,10 @@ static void srcu_gp_end(struct srcu_struct *ssp, bool is_atomic) /* Initiate callback invocation as needed. */ ss_state = smp_load_acquire(&sup->srcu_size_state); - if (ss_state < SRCU_SIZE_WAIT_BARRIER) { + if (!is_atomic && ss_state < SRCU_SIZE_WAIT_BARRIER) { srcu_schedule_cbs_sdp(per_cpu_ptr(ssp->sda, get_boot_cpu_id()), cbdelay); - } else { + } else if (!is_atomic) { idx = rcu_seq_ctr(gpseq) % ARRAY_SIZE(snp->srcu_have_cbs); srcu_for_each_node_breadth_first(ssp, snp) { raw_spin_lock_irq_rcu_node(snp); -- 2.40.1