Documentation/io_ordering.txt is wrong

Matthew Wilcox
2004-09-18T17:57:16Z

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