Re: [PATCH v2 6/7] s390/pci: Set MSI_FLAG_NO_AFFINITY at IRQ init time

[sashiko-bot@kernel.org]

> 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.
> 
> Signed-off-by: Tobias Schumacher <ts@linux.ibm.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20261005-s390_irq_domain_fixes-v2-0-d45b824874c0@linux.ibm.com?part=6