Re: [v2] powerpc/powernv/pci: Work around races in PCI bridge enabling

On Fri, 2018-08-17 at 07:30:39 UTC, Benjamin Herrenschmidt wrote:

The generic code is race when multiple children of a PCI bridge try to
enable it simultaneously.

This leads to drivers trying to access a device through a not-yet-enabled
bridge, and this EEH errors under various circumstances when using parallel
driver probing.

There is work going on to fix that properly in the PCI core but it will
take some time.

x86 gets away with it because (outside of hotplug), the BIOS enables all
the bridges at boot time.

This patch does the same thing on powernv by enabling all bridges that
have child devices at boot time, thus avoiding subsequent races. It's suitable
for backporting to stable and distros, while the proper PCI fix will probably
be significantly more invasive.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: stable@vger.kernel.org

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/db2173198b9513f7add8009f225afa

cheers