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 48BD3326951; 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=1789778144; cv=none; b=P2Qy+qB2tybqM0dUWwppqsonI9dvFPBwlAaj8xt10zHgHQb1n6hONvMpG7/yxrYvBzfScJv8BvwtFORP2re3fNFxqHfOv0hMAX++eiYOxewu/sjgq/UfPk7XxW2OtjN+1MULnjmbClGzw/YPUQJfnJKegc+j5jpxK1XcIb8dYPw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789778144; c=relaxed/simple; bh=R62qS2zKFtOpdiEqV9ZFD2Tiav/SDiJXzxwuevtgBVg=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=rHR2e/qPis2Kw6qDW3EPocPsu/4CbZa91DC3G6HralUjm0QFVTZ3sXD8tQon2eOO+qqEjxOw7v+LdvKt49jESK7N2ipZ0KDmVxaJH/Hur8DBeuWdZph3+I5SiXKCsbU7fvgBVM7vVOCQ/+oqSylGBHR8aMEGakVaQqJjM1BEo0A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dg+U9/dw; 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="dg+U9/dw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4C9D11F008AB; 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=SYTCZikcR2BFsI4FpUwyomm1XM+SLtLcZIqlQqV2aSs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=dg+U9/dwE5OOSeIbkinkBLY4xiKUg9T+DZYxTwoyIGvMZv9FqsEYFEWeuhAWhVeqd oOmEwFqNmwtdiWOw4jbT7H2Fhr5SS4/okZG0OTz5g7Y7GfhlO3Uq+A3wBJdyBmnBJi FJStEHEUf+zNiwLT9ZpimCBbuNJRzMFw7sv/WUWTPcUt4ZqfF3eqMBZR/X6+WxlyRm WneuhKsJw7FhlC2sJY7m1ZK5kurM3Iqtax9Dy9Wgbu4DWe1RBb9VIhMru9EqjMPk13 jxIrY/x7TYVrooDp1F48EQJhhpvyjSIMQnVm1Ztf36Y1i8kJZaVb2p/3cInMjpzypf UPjMS5YzYGRTA== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id B80DECE1A13; 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 15/19] srcutree: Remove srcu_barrier() sleep for atomic SRCU Date: Fri, 18 Sep 2026 17:35:17 -0700 Message-Id: <20260919003521.3134552-15-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 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 0954486880c7..82e61421142e 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