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 D59CA41C30F; Wed, 7 Oct 2026 20:59:27 +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=1791406769; cv=none; b=ehcS7/oo2d0iDAa/ujkqGchBlgA+aZjJmmtsel4Zu1T1rtB5j3DEBm8jh/B+JBvptr18Nwl+ca84KaHJ7B2X4fSVFcg3OUPGbxWlr49CRtJaBIwWGBNS0WyHDp9xlv4xPzCdGZgUwkXJLthwMjj9WR93mFE9QCsiRazJridIKMM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791406769; c=relaxed/simple; bh=d2jkGQSCU3DYwpz+ezO2oQr1lWXD4kYhearCA6KtS0g=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=YriuuvvL/jckLLMGNSqQEViBCHNHatD8hvqilJRgwe3as9aamOcbSy/8SHXi2Li9KQfDgCJfsCfA3QpuwwHvWHMVl9iQcNbUYRsX8vz9X7XzBcQ5YV46VwmQMK944Ym1ixRdILXlKdV/ghV6Qf8QlnnGq9fZsCM/4bqprqiuNjQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KZwIiVKC; 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="KZwIiVKC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CB85F1F008A6; Wed, 7 Oct 2026 20:59:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791406765; bh=NUlmnlkNd4HmlXKm8CflXWJ7cxKje+bzKwecoFTrkYA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=KZwIiVKCEwXuBLrmGzwuKG/mk3VMt3dCWbgkjRe8dcrFceSlNRHORhCnCFDJWXeOS t3BvouW4cPplKkusHy46kzdj19kiw3AiPVY2v43mL/5tslgoQMODUN/G1u3Kv9BW3g 9ImGUaB4IKxcIfskOnBHpX0TLP8xzCrL+WJrWD2ZsSlzmKIyTbvE8GQ37v/uMUEQRp WPrxVfrtje4HEhiGOoSmVxLNEo91tfN/Ug2m4JaITGoDkoKwyXHrgJfpqx8rzQjQsl XejMjCvwpFje2TFxJz+s1G+KRybDGXgqwr8oBGpESxz0pOUmaU8jIu486RgIH+/ktC N33uX8n3sbn4Q== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 33236CE3992; Wed, 7 Oct 2026 13:59:25 -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 v2 14/21] srcutree: Remove srcu_barrier() sleep for atomic SRCU Date: Wed, 7 Oct 2026 13:59:17 -0700 Message-Id: <20261007205924.1983367-14-paulmck@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <546c81a7-f677-4d8e-a304-746b227058b0@paulmck-laptop> References: <546c81a7-f677-4d8e-a304-746b227058b0@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 The atomic-SRCU path in srcu_barrier() sleeps for 100 milliseconds just in case there are callbacks to wait for. But call_srcu() refuses atomic SRCU with a WARN_ON_ONCE() before reaching the deferred-enqueue path, so there can be no callbacks, deferred or otherwise. Drop the sleep. Signed-off-by: Kunwu Chan Signed-off-by: Paul E. McKenney --- kernel/rcu/srcutree.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 0954486880c7d..82e61421142e5 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -1892,12 +1892,9 @@ void srcu_barrier(struct srcu_struct *ssp) unsigned long s; check_init_srcu_struct(ssp, false); - if (WARN_ON_ONCE(ssp->srcu_reader_flavor == SRCU_READ_FLAVOR_ATOMIC)) { - // There shouldn't be any callbacks for atomic SRCU, - // but just in case. - schedule_timeout_uninterruptible(HZ/10); + // Atomic SRCU has no callbacks, so there is nothing to wait on. + if (WARN_ON_ONCE(ssp->srcu_reader_flavor == SRCU_READ_FLAVOR_ATOMIC)) return; - } /* * Register any deferred callbacks before snapshotting the sequence. The -- 2.40.1