s390/pci: Set MSI_FLAG_NO_AFFINITY at IRQ init time

MSI_FLAG_NO_AFFINITY is added to zpci_msi_parent_ops.required_flags from
zpci_create_parent_msi_domain(), which runs for every new PCI bus,
including buses created at runtime from a hotplug availability event.

That is a non-atomic read-modify-write on a field which
msi_lib_init_dev_msi_info() reads without a common lock while setting up
MSI for a device on an already existing bus:

      required_flags = pops->required_flags;

The stored value is always the same, so no caller observes a change, but
the race need not exist: irq_delivery is decided once in zpci_irq_init()
and never changes afterwards.

Set the flag there instead, before any parent domain exists.

Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Tobias Schumacher <ts@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

0 files changed, 0 insertions, 0 deletions