linux-kernel - Re: [PATCH v3 3/4] scsi: core: Cap shost max_sectors according to DMA optimum mapping limits

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <fe365aa8-00d5-153d-ceb2-f887a71a6927@acm.org>
Date:   Wed, 8 Jun 2022 10:33:26 -0700
From:   Bart Van Assche <bvanassche@....org>
To:     John Garry <john.garry@...wei.com>,
        damien.lemoal@...nsource.wdc.com, joro@...tes.org, will@...nel.org,
        jejb@...ux.ibm.com, martin.petersen@...cle.com, hch@....de,
        m.szyprowski@...sung.com, robin.murphy@....com
Cc:     linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-ide@...r.kernel.org, iommu@...ts.linux-foundation.org,
        linux-scsi@...r.kernel.org, liyihang6@...ilicon.com,
        chenxiang66@...ilicon.com, thunder.leizhen@...wei.com
Subject: Re: [PATCH v3 3/4] scsi: core: Cap shost max_sectors according to DMA
 optimum mapping limits

On 6/6/22 02:30, John Garry wrote:
> +	if (dma_dev->dma_mask) {
> +		shost->max_sectors = min_t(unsigned int, shost->max_sectors,
> +				dma_opt_mapping_size(dma_dev) >> SECTOR_SHIFT);
> +	}

Since IOVA_RANGE_CACHE_MAX_SIZE = 6 this limits max_sectors to 2**6 * 
PAGE_SIZE or 256 KiB if the page size is 4 KiB. I think that's too 
small. Some (SRP) storage arrays require much larger transfers to 
achieve optimal performance.

Thanks,

Bart.