RE: [PATCH v4] drivers/block/mtip32xx: Adding new driver mtip32xx

From: Sam Bradshaw (sbradshaw)
Date: Fri Sep 09 2011 - 11:16:13 EST



> 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.
>
> > - Given that the driver has a single c implementation file all
symbols
> > should be marked static, and there should be no prototypes in the
> > header
>
> Sam, would be nice if you could send in patches for the other bugs
that
> Christoph have pointed out. I already found and fixed the flush parts.

Will do. I'll send out patches against for-3.2/mtip32xx, given that
Jens has already made some changes.

Thanks for the tip on sparse endianness checking. I wasn't aware of
this tool until now.

-Sam


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