tree a4bea1a5cdbfd8321463cc50b5539bebd4b01155
parent dc87c3985e9b442c60994308a96f887579addc39
author Mitch Williams <mitch.a.williams@intel.com> 1175280848 -0700
committer Greg Kroah-Hartman <gregkh@suse.de> 1178157754 -0700

PCI: Flush MSI-X table writes

This patch fixes a kernel bug which is triggered when using the
irqbalance daemon with MSI-X hardware.

Because both MSI-X interrupt messages and MSI-X table writes are posted,
it's possible for them to cross while in-flight.  This results in
interrupts being received long after the kernel thinks they're disabled,
and in interrupts being sent to stale vectors after rebalancing.

This patch performs a read flush after writes to the MSI-X table for
mask and unmask operations.  Since the SMP affinity is set while
the interrupt is masked, and since it's unmasked immediately after,
no additional flushes are required in the various affinity setting
routines.

This patch has been validated with (unreleased) network hardware which
uses MSI-X.

Revised with input from Eric Biederman.

Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>