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SubjectRe: [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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