From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH v4] drivers/block/mtip32xx: Adding new driver mtip32xx Date: Tue, 13 Sep 2011 08:49:06 -0400 Message-ID: <20110913124906.GA17855@infradead.org> References: <22A973199D2C2F46933448F6E7990A3002C80026@ntxboimbx31.micron.com> <4E44E782.7090309@fusionio.com> <2A9BE4FF6209B644B6F8EB62DE6AEA1E07663ED4@ntxfrembx01.micron.com> <20110909085433.GA9593@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from 173-166-109-252-newengland.hfc.comcastbusiness.net ([173.166.109.252]:60082 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753321Ab1IMMtO (ORCPT ); Tue, 13 Sep 2011 08:49:14 -0400 Content-Disposition: inline In-Reply-To: <20110909085433.GA9593@infradead.org> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: "Sam Bradshaw (sbradshaw)" Cc: jaxboe@fusionio.com, alan@lxorguk.ukuu.org.uk, hch@infradead.org, linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org, Jeff Garzik , jmoyer@redhat.com, "Asai Thambi Samymuthu Pattrayasamy (asamymuthupa) [CONTRACTOR]" Btw, there is another _huge_ issue with the driver, and that is the lack of any internal queueing. Remember the make_request interface is an extremly thin layer (or rather the lack of it) below the filesystem. So for example if eh_active is non-zero you return -EBUSY to the filesystems. That's an error code it a) doesn't recognize and b) couldn't handle even if it did. Similarly mtip_hw_get_scatterlist simply blocks if no tag is currently available instead of queueing it up.