linux-kernel - Re: [PATCH v4] drivers/block/mtip32xx: Adding new driver mtip32xx

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Date:	Fri, 30 Sep 2011 13:49:30 -0600
From:	Asai Thambi S P <asamymuthupa@...ron.com>
To:	Jens Axboe <jaxboe@...ionio.com>
CC:	Christoph Hellwig <hch@...radead.org>,
	"Sam Bradshaw (sbradshaw)" <sbradshaw@...ron.com>,
	"alan@...rguk.ukuu.org.uk" <alan@...rguk.ukuu.org.uk>,
	"linux-ide@...r.kernel.org" <linux-ide@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Jeff Garzik <jgarzik@...ox.com>,
	"jmoyer@...hat.com" <jmoyer@...hat.com>
Subject: Re: [PATCH v4] drivers/block/mtip32xx: Adding new driver mtip32xx

On 9/9/2011 2:58 AM, Jens Axboe wrote:
> On 2011-09-09 10:54, Christoph Hellwig wrote:
>> On Mon, Aug 22, 2011 at 02:28:11PM -0700, Sam Bradshaw (sbradshaw) wrote:
>>> New patch for mtip32xx driver based on feedback from
>>> Jens Axboe, Christoph Hellwig, and Alan Cox.
>>
>> A few comments that need addressing:
>>
>>  - the ioctl handler always returns 0 for the BLKFLSBUF ioctl, without
>>    doing anything.  Given that the ioctl is supposed to flush all kinds
>>    of higher level cached data this is a serious data integrity issue.
>>    It must simply do the default -ENOTTY return for it and let the block
>>    layer do the right thing.
>>  - handling of REQ_FUA / REQ_FLUSH requests is completely broken.
>>    There is a weird barrier flag to mtip_hw_submit_io which set the
>>    hwardware FUA bit if the FLUSH bit is set on a request.
>>    Please take a look at how this should be handled, the
>>    Documentation/block/writeback_cache_control.txt file is the canonical
>>    resource.  Implementing your driver at the make_request layer
>>    unfortunately means you will have to do all the hard work yourself.
>>  - also the call to blk_queue_flush(queue, 0); from ->make_request for
>>    a non-data request is completely wrong.
> 
> I noticed both of these flush/fua problems too and have fixed them up.
> 
>>  - the 64-bit case in fill_command_sg will blow up on big endian
>>    systems, please use your current 32-bit case unconditionally
>>  - mtip_block_getgeo should just use sector_div instead of the ifdef
>>    mess.
>>  - please check the driver using sparse, and most importantly the
>>    optional endianess checking pass of it.  Currently the driver
>>    uses plain unsigned int and similar types for little endian
>>    hardware structures.  Take a look at Documentation/sparse.txt
>>    on how to use it.
>>  - the mtip_check_surprise_removal check should be unconditional, not
>>    under #ifdef CONFIG_HOTPLUG
> 
> In general, the dependency on HOTPLUG_PCI_PCIE is odd as well.

For the device to support surprise removal and surprise insertion
(SRSI), need pciehp module loaded.


-- 
Regards,
Asai Thambi
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