From mboxrd@z Thu Jan 1 00:00:00 1970 From: Boaz Harrosh Subject: Re: memory allocation in sg_io() Date: Thu, 10 Jan 2008 15:05:25 +0200 Message-ID: <47861815.5090008@panasas.com> References: <200801101333.12293.oliver@neukum.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from gw-colo-pa.panasas.com ([66.238.117.130]:2889 "EHLO cassoulet.panasas.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754040AbYAJNFi (ORCPT ); Thu, 10 Jan 2008 08:05:38 -0500 In-Reply-To: <200801101333.12293.oliver@neukum.org> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Oliver Neukum Cc: axboe@kernel.dk, SCSI development list On Thu, Jan 10 2008 at 14:33 +0200, Oliver Neukum wrote: > Hi, > > could you explain to me why this code can get away with allocating the > sense buffer on the stack? > > static int sg_io(struct file *file, struct request_queue *q, > struct gendisk *bd_disk, struct sg_io_hdr *hdr) > { > unsigned long start_time; > int writing = 0, ret = 0, has_write_perm = 0; > struct request *rq; > char sense[SCSI_SENSE_BUFFERSIZE]; > > Regards > Oliver > - where? what? do you mean in scsi_ioctl.c? why not it's a synchronous call? Do you mean 96 bytes is too big? Do you mean DMA alignment and cache coherency? I'm working on that for scsi devices. Boaz