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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 601EBC31E5B for ; Mon, 17 Jun 2019 20:56:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 378B92080A for ; Mon, 17 Jun 2019 20:56:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726088AbfFQU4h (ORCPT ); Mon, 17 Jun 2019 16:56:37 -0400 Received: from mail-pl1-f195.google.com ([209.85.214.195]:43406 "EHLO mail-pl1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725497AbfFQU4g (ORCPT ); Mon, 17 Jun 2019 16:56:36 -0400 Received: by mail-pl1-f195.google.com with SMTP id cl9so4638398plb.10; Mon, 17 Jun 2019 13:56:36 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=oaUF+IVfxLkFEOX3EdWdqY0MW6ieO175zRASbw5HHZM=; b=In45RciiYycSqmGUdJVle6PXKgp27Jun83jcfNaFIWxUh+nu6S7hGEwwIyxJocZJWT mGlVFcevrfTBcxOXw6X2qvuIfTNXez1swbd03ntboTL0nem4WZrx31X4pjJoP84AKVFi L+eU+ocYLl2Pe1qZ5fnOTe3E0DcC8zXsZVBXwB2Ia7EiEyTvkvN0SBnGM1OJanw1gcjt gnbH6CCtegHpz+1xeU4F84+YmRqccWdXELzmRCC0iBnIl6FtWwwgM0a1hZevfmCcY+1b 7EefNT9Nm4Z6LbhWq7o8I+0WNkpcFfqD5jRPBKISAGXGFBPwESwFRXQlBl1rMMNr4q6H UDjA== X-Gm-Message-State: APjAAAUTYWWzYCdpFb0vIbIXNS+5KK8cfm63DuzxCzC/U+utgDZMWRsB lcoXQEJNarAhpKJpZFg2H4oe09jTYuI= X-Google-Smtp-Source: APXvYqyW1uX5YVD0oJTXzOf/KTeNCXdXhtPN2mMaP3rKDVGtTCu0tZAI6kQEifd7AGUdvUb3udfRmg== X-Received: by 2002:a17:902:760a:: with SMTP id k10mr89887792pll.83.1560804995269; Mon, 17 Jun 2019 13:56:35 -0700 (PDT) Received: from desktop-bart.svl.corp.google.com ([2620:15c:2cd:202:4308:52a3:24b6:2c60]) by smtp.gmail.com with ESMTPSA id r9sm12006074pgv.24.2019.06.17.13.56.33 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Mon, 17 Jun 2019 13:56:34 -0700 (PDT) Subject: Re: [PATCH 2/8] scsi: take the DMA max mapping size into account To: Christoph Hellwig , "Martin K . Petersen" Cc: Sagi Grimberg , Max Gurtovoy , linux-rdma@vger.kernel.org, linux-scsi@vger.kernel.org, megaraidlinux.pdl@broadcom.com, MPT-FusionLinux.pdl@broadcom.com, linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org References: <20190617122000.22181-1-hch@lst.de> <20190617122000.22181-3-hch@lst.de> From: Bart Van Assche Message-ID: <5d143a03-edd5-5878-780b-45d87313a813@acm.org> Date: Mon, 17 Jun 2019 13:56:32 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20190617122000.22181-3-hch@lst.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-hyperv-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org On 6/17/19 5:19 AM, Christoph Hellwig wrote: > We need to limit the devices max_sectors to what the DMA mapping > implementation can support. If not we risk running out of swiotlb > buffers easily. > > Signed-off-by: Christoph Hellwig > --- > drivers/scsi/scsi_lib.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c > index d333bb6b1c59..f233bfd84cd7 100644 > --- a/drivers/scsi/scsi_lib.c > +++ b/drivers/scsi/scsi_lib.c > @@ -1768,6 +1768,8 @@ void __scsi_init_queue(struct Scsi_Host *shost, struct request_queue *q) > blk_queue_max_integrity_segments(q, shost->sg_prot_tablesize); > } > > + shost->max_sectors = min_t(unsigned int, shost->max_sectors, > + dma_max_mapping_size(dev) << SECTOR_SHIFT); > blk_queue_max_hw_sectors(q, shost->max_sectors); > if (shost->unchecked_isa_dma) > blk_queue_bounce_limit(q, BLK_BOUNCE_ISA); Does dma_max_mapping_size() return a value in bytes? Is shost->max_sectors a number of sectors? If so, are you sure that "<< SECTOR_SHIFT" is the proper conversion? Shouldn't that be ">> SECTOR_SHIFT" instead? Additionally, how about adding a comment above dma_max_mapping_size() that documents the unit of the returned number? Thanks, Bart.