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 7C1D1C35FF3 for ; Fri, 21 Mar 2025 06:05:59 +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=YMFDUMWG3K3wYoSwxMOqac1Pz5RML07A7BlmLdz1jpE=; b=AZnzfBm8wCTrUE4NXJzWAlwWRy NMaObDmzPVlW9CxsGTkJpQGgPMgnjAA/v3yTw96VN+yy5WEjhxqbyZEEsyRX/P9yRA4t1vnihErrO b8dnRYVzeoNmWxvNlWV/wYNRUG72XZa8XLBP0CaN6Im6CiohDsVzj8jgxvgGromoBV06tAZ6yOght +I1KqteUsCVGXJBIYMwmcpse06UQOOeWanTR/ih/dEoAnwiosSZlgb3BY/ur7TBthNqHtx+W5UwSW VXWXzeCMgz8OOUlJtL9NLMaI6gys0cVGUUIQhxe6zs+QhFVih/5cPhIQ2TdUhMPB5miboLXSs1rXu AtyxgXkg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tvVW1-0000000DwxO-1tMv; Fri, 21 Mar 2025 06:05:57 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tvVVz-0000000Dwwo-0PxB for linux-nvme@lists.infradead.org; Fri, 21 Mar 2025 06:05:56 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id F0B1D68AA6; Fri, 21 Mar 2025 07:05:50 +0100 (CET) Date: Fri, 21 Mar 2025 07:05:50 +0100 From: Christoph Hellwig To: Daniel Wagner Cc: Hannes Reinecke , Daniel Wagner , James Smart , Christoph Hellwig , Sagi Grimberg , Chaitanya Kulkarni , Keith Busch , linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 04/18] nvmet-fcloop: refactor fcloop_nport_alloc Message-ID: <20250321060550.GC3007@lst.de> References: <20250318-nvmet-fcloop-v3-0-05fec0fc02f6@kernel.org> <20250318-nvmet-fcloop-v3-4-05fec0fc02f6@kernel.org> <66261f08-5386-4b22-aa6f-7be1d4023fee@flourine.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <66261f08-5386-4b22-aa6f-7be1d4023fee@flourine.local> 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-20250320_230555_277425_6E5D630E X-CRM114-Status: GOOD ( 16.09 ) 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 Tue, Mar 18, 2025 at 02:38:56PM +0100, Daniel Wagner wrote: > This means the new entry has always to be allocated first and then we > either free it again or insert into the list, because it's not possible > to allocate under the spinlock. Not that beautiful but correctness wins. Yes, we do that a lot. And if finding an existing entry is the more common outcome (I don't think it is here, but I'm not sure), you do a search first, allocate, and then search again.