From mboxrd@z Thu Jan 1 00:00:00 1970 From: FUJITA Tomonori Subject: Re: [PATCH] 2.6.25-rc4-git3 - inquiry cmd issued via /dev/sg? device causes infinite loop in 2.6.24 Date: Tue, 18 Mar 2008 09:48:25 +0900 Message-ID: <20080318094816C.tomof@acm.org> References: <47D7035F.5000700@sgi.com> <47DEB3A7.1030600@cs.wisc.edu> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: Received: from mo10.iij4u.or.jp ([210.138.174.78]:51064 "EHLO mo10.iij4u.or.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753021AbYCRAtJ (ORCPT ); Mon, 17 Mar 2008 20:49:09 -0400 In-Reply-To: <47DEB3A7.1030600@cs.wisc.edu> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: michaelc@cs.wisc.edu Cc: mdr@sgi.com, dougg@torque.net, linux-scsi@vger.kernel.org, jeremy@sgi.com, James.Bottomley@SteelEye.com, tomof@acm.org On Mon, 17 Mar 2008 13:08:39 -0500 Mike Christie wrote: > Michael Reed wrote: > > - ++blk_size; /* don't know why */ > > -/* round request up to next highest SG_SECTOR_SZ byte boundary */ > > I think we can remove this code. This was asked before, and here is > Doug's reply: > http://www.mail-archive.com/linux-scsi@vger.kernel.org/msg11757.html > > It was probaly due to some weirdness in that the scatterlist that sg.c > made used to be sent directly to the LLD (now it is only used to > hold/organize the pages/segments that the sg and st driver manages in > their internal reserves), or maybe it had something to do with that and > dma alignment problems or something. I really have no idea, but the > block layer SG IO code has not been rounding up in its indirect path and > it has been fine. The block layer (blk_rq_map_user) does padding for LLDs, I guess.