Re: [PATCH v18 11/13] PCI: Cache PCI DSN into pci_dev->dsn during probe

> Subsequent CXL error-reporting code paths need to log the PCI Device
> Serial Number (DSN) as part of trace events emitted from interrupt or
> panic context. Computing the DSN there via pci_get_dsn() requires PCI
> configuration space reads, which are slow, can fail when the link is
> down or frozen, and may not be safe in some contexts.
> 
> Add a u64 dsn field to struct pci_dev and populate it from pci_get_dsn()
> during pci_init_capabilities() at probe time via pci_dsn_init(). Only
> write dev->dsn when the read succeeds. The zero initial value from
> pci_dev allocation already represents 'no DSN available.'
> 
> pci_get_dsn() is not modified because it remains a pure config-space read
> with no side effects on pci_dev. The cache is written exclusively by
> pci_dsn_init() at probe time.
> 
> Signed-off-by: Terry Bowman <[email protected]>

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

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