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But really locking is unnecessary here: > We're running with pcidevs_lock held (i.e. multiple invocations of the > same function [or their teardown equivalents] are impossible, and hence > there are no "local" races), while all consuming of the data being > populated here can't race anyway due to happening sequentially > afterwards. See also the comment in struct arch_pci_dev. I would explicitly say that none of the code in the locked region touches any data in the domain_iommu struct, so taking the mapping_lock is unneeded. Long term we might wish to implemented a per-device lock that could be used here, instead of relying on the pcidevs lock. > > Signed-off-by: Jan Beulich Reviewed-by: Roger Pau Monné Thanks, Roger.