From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 94888C4332F for ; Mon, 21 Nov 2022 07:41:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:References: List-Owner; bh=YZOr4dqWY6A4IYjzyjJAX4AuaRMVwaVU935IQJ9xfZQ=; b=38WugZkEnX+aAl sBemofo19WRpBWKIZ6OZOEttdnfeUmiRTekBGky1euLJW7jje4g4tpgBPrYTKfF/kJl3eRZoJEaO5 uoUPwMTDEFRATcYN/LwGRu/EVt4TLDgSj/NmhkZY9iMC4YxQ0Fcpwn7uoUIr1PBg4CC6wEAYRVN/q TRqBfse13n7IWQ9k7LhGTP1GoPFno8uGLFSO6DJwmfWUmBXJw0cQFoJ8pAO3fnqSvg5HF7n7MDgeB /V5UqKL+yWhhrOwzlZF/KNtTQfUidNExknACnXVR6uuzoPRJ7ejJ27EC1jH1GcFvSp5QVDqWi3sbX a6Xl43HsZwzz+CgE8IVA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1ox1QH-00AUOM-HR; Mon, 21 Nov 2022 07:40:57 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1ox1Q6-00AUDr-JY for linux-nvme@lists.infradead.org; Mon, 21 Nov 2022 07:40:47 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 2DCDB68AA6; Mon, 21 Nov 2022 08:40:40 +0100 (CET) Date: Mon, 21 Nov 2022 08:40:39 +0100 From: Christoph Hellwig To: Sagi Grimberg Cc: Caleb Sander , Keith Busch , Jens Axboe , Christoph Hellwig , linux-nvme@lists.infradead.org, Uday Shankar , "Paul E. McKenney" Subject: Re: [PATCH] nvme: fix SRCU protection of nvme_ns_head list Message-ID: <20221121074039.GA24507@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221120_234046_823119_5EFE8C0A X-CRM114-Status: GOOD ( 14.38 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Sun, Nov 20, 2022 at 01:24:51PM +0200, Sagi Grimberg wrote: >> sector_t capacity = get_capacity(head->disk); >> int node; >> + int srcu_idx; >> + srcu_idx = srcu_read_lock(&head->srcu); >> list_for_each_entry_rcu(ns, &head->list, siblings) { >> if (capacity != get_capacity(ns->disk)) >> clear_bit(NVME_NS_READY, &ns->flags); >> } >> + srcu_read_unlock(&head->srcu, srcu_idx); > > I don't think you need srcu here, rcu_read_lock/unlock is sufficient. So the code obviously does not sleep. But I wonder if anything speaks against mixing SRCU and RCU protection for the same list?