dtbs_install recursing on subdirs-y and dtbs-subdir leading to race?

[ijc@debian.org (Ian Campbell)]

On Wed, 2016-03-16 at 09:04 +0000, Russell King - ARM Linux wrote:
> On Wed, Mar 16, 2016 at 08:54:34AM +0000, Ian Campbell wrote:
> > Where it appears that multiple instance of __dtbs_install_prep have
> > been running in parallel at least the apm and arm subdirectories of
> > arch/arm64/boot/dts, with both of them then racing in the?
> >?????$(Q)if [ -d $(INSTALL_DTBS_PATH) ]; then mv
> $(INSTALL_DTBS_PATH) $(INSTALL_DTBS_PATH).old; fi
> > rule since apparently $(INSTALL_DTBS_PATH) existed during the "-d"
> > check but had gone by the time of the move.
> 
> I've already sent a patch several times to remove this line, I believe
> it's finally queued for this merge window.

Yes, as I said further down in my mail:

    I understand that the mv bit of the rule in question is likely to be
    removed quite soon[1] but I think the underlying race / extra recursion
    still exits and might have other implications.

(where [1] was a link to your patch).

I still think it is unexpected (or at least unintended) that this rune
is run in all subdirectories.

Ian.