Documentation/io_ordering.txt is wrong

[Matthew Wilcox <willy@debian.org>]

On Sat, Sep 18, 2004 at 12:10:01AM -0600, Grant Grundler wrote:
> Jesse Barnes wrote:
> ...
> > Btw Andrew (Vasquez), there's a small doc I put together that should describe 
> > when you have to worry about PCI posting.  It's in the tree:  
> > Documentation/io_ordering.txt.  If it's incomplete or confusing, just let me 
> > know and I'll update it.
> 
> Jesse,
> Both. incomplete and confusing.
> "concrete example of a hypothetical driver" wasn't my first warning
> this document needed work. :^)

Not just incomplete and confusing, but actively wrong.  spin_lock/
spin_unlock should imply ordering of readb().  What you're describing
there is __readb().  See Documentation/DocBook/deviceiobook.tmpl.  Also,
rmb() should ensure ordering of io reads; there should be no need to
touch the device.

-- 
"Next the statesmen will invent cheap lies, putting the blame upon 
the nation that is attacked, and every man will be glad of those
conscience-soothing falsities, and will diligently study them, and refuse
to examine any refutations of them; and thus he will by and by convince 
himself that the war is just, and will thank God for the better sleep 
he enjoys after this process of grotesque self-deception." -- Mark Twain