Re: [RFC PATCH 1/6] Revert "PCI: Fix is_added/is_busmaster race condition"

[Bjorn Helgaas]

On Sat, Aug 18, 2018 at 01:24:51PM +1000, Benjamin Herrenschmidt wrote:
> On Fri, 2018-08-17 at 10:44 -0500, Bjorn Helgaas wrote:
> > On Fri, Aug 17, 2018 at 02:48:57PM +1000, Benjamin Herrenschmidt wrote:
> > > This reverts commit 44bda4b7d26e9fffed6d7152d98a2e9edaeb2a76.
> > 
> > Just to be clear, if I understand correctly, this is a pure revert of
> > 44bda4b7d26e and as such it reintroduces the problem solved by that
> > commit.
> > 
> > If your solution turns out to be better, that's great, but it would be
> > nice to avoid the bisection hole of reintroducing the problem, then
> > fixing it again later.
> 
> There is no way to do that other than merging the revert and the fix
> into one. That said, the race is sufficiently hard to hit that I
> wouldn't worry too much about it.

OK, then at least mention that in the changelog.

> > > The new pci state mutex provides a simpler way of addressing
> > > this race and avoids the relative includes added to the powerpc
> > > code.
>