Jiri Pirko
477f84cf91
Some drivers expose sub-functions (SFs) of a PCI Physical or Virtual Function as auxiliary devices that carry a stable 'sfnum' sysfs attribute — the user-defined sub-function number (e.g. the value passed to "devlink port add ... sfnum N"). The SF's leaf devices (uverbs, infiniband, net, ...) sit below this aux device in sysfs: /sys/devices/.../<PF or VF BDF>/<sf aux>/.../<leaf> Currently path_id walks straight past the aux device, so all leaf devices below an SF end up sharing ID_PATH=pci-<BDF> with their parent PF or VF. For uverbs this causes a /dev/infiniband/by-path/ symlink collision, and for any other consumer of ID_PATH/ID_PATH_TAG it makes PF and SF (or VF and VF-SF) indistinguishable. Recognise the 'auxiliary' subsystem in path_id's walk: when the aux device exposes 'sfnum', prepend an 'sf-<N>' token; otherwise leave it untokenised. The result for an SF whose parent PF is at PCI 0000:c1:00.0 and which was added with "sfnum 88" is: ID_PATH=pci-0000:c1:00.0-sf-88 ID_PATH_TAG=pci-0000_c1_00_0-sf-88 This is parallel to how net_id's NAMING_SUBFUNC scheme appends 'S<N>' on top of the PF base name. Aux devices without 'sfnum' keep the pre-patch behaviour: the walk skips over them with no token. Existing ID_PATH values for PF and VF leaf devices are therefore unchanged, the change is purely additive, and there is no need to gate it behind a naming scheme (path_id itself is unversioned). Co-developed-by: Claude Opus 4.7 <noreply@anthropic.com>
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