Hello, Christoph.

On Sat, Oct 03, 2015 at 07:21:10PM +0200, Christoph Hellwig wrote:

Without this the SCSI midlayer can race and queue another command
before the tag data has been released, which could lead to incorrect
manipulation of the ata command state.

Signed-off-by: Christoph Hellwig <hch@lst.de>

Hmmm... has this actually been observed?  All these are run under ata
port lock and so is the command issue path, so even if the tag gets
reissued, it will have to wait till the completion path is done.

Thanks.

-- 
tejun