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 09BACC4332F for ; Tue, 29 Nov 2022 08:39:20 +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:References: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:List-Owner; bh=zDzP+Gvd21EQF+auiWUM6KdxZ18F/5sPQ9Wt+bKbjpM=; b=hKQlaehTkE8jmiMiYFxZhKCB08 J0XTSG2oZHUIkRFVK9fp9i/XIulV76tB0SA+rAj1WrGpz9nymq3oUbjAyu5XVGwpB28RJSbG3/32s 75QgbBP+icr6X8GZAFOpHjBUVTx/rxdBXDLOVceeJ6oPe3oQl0hUTgx9pwrmkaeZ7iNe8yt5p2HI4 9DXyfYh3RfCXHyRDQ11nGrHW9ZSTEt+BvLV5uSv1y1QK5CPI03qCKFn6UdPIviCR94+OLgTRc51W2 /GmkW0j8V7F9oY6xsgPY5c/dDss40DVEZGPiHJ2YiimcqlEoaYMN4gDhc1xRpDqfIlugioOeHVATi 49zR1HxQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1ozw97-007R2W-D8; Tue, 29 Nov 2022 08:39:17 +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 1ozw90-007Qzz-MR for linux-nvme@lists.infradead.org; Tue, 29 Nov 2022 08:39:11 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 5BB6268AFE; Tue, 29 Nov 2022 09:39:06 +0100 (CET) Date: Tue, 29 Nov 2022 09:39:05 +0100 From: Christoph Hellwig To: Caleb Sander Cc: Keith Busch , Jens Axboe , Christoph Hellwig , Sagi Grimberg , linux-nvme@lists.infradead.org, Uday Shankar Subject: Re: [PATCH] nvme: fix (S)RCU protection of nvme_ns_head list (alternate) Message-ID: <20221129083905.GA25314@lst.de> References: <20221118232756.1457075-1-csander@purestorage.com> <20221124002432.3715594-1-csander@purestorage.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221124002432.3715594-1-csander@purestorage.com> 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-20221129_003910_890975_4C225AFA X-CRM114-Status: GOOD ( 13.37 ) 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 Wed, Nov 23, 2022 at 05:24:32PM -0700, Caleb Sander wrote: > +++ b/drivers/nvme/host/multipath.c > @@ -175,10 +175,12 @@ void nvme_mpath_revalidate_paths(struct nvme_ns *ns) > sector_t capacity = get_capacity(head->disk); > int node; > > + rcu_read_lock(); > list_for_each_entry_rcu(ns, &head->list, siblings) { > if (capacity != get_capacity(ns->disk)) > clear_bit(NVME_NS_READY, &ns->flags); > } > + rcu_read_unlock(); I can't see how protection iteraction of the same list once with SRCU and once with RCU can work in practice.