DRAFT: kill giant - part 1 - #2399
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Every Giant acquisition in this file is a bus topology lock: creating and destroying VF children mutates the device tree, and pci_iov_config(), pci_iov_delete() and the two ioctl paths all reach into it. Use the handle that says so. No functional change: bus_topo_lock() is still &Giant today. Converting the callers is a prerequisite for giving the topology lock its own sx, which is tracked in design/giant-removal-strategy.md. Note for that later change: pci_iov_config() calls pause() for the 100 ms the SR-IOV specification requires before VFs may be accessed, and does so with the lock held. Giant is silently dropped there today; an sx will not be, so the lock will need to be dropped and retaken around the pause. The region is already protected by IOV_BUSY, so that is safe. Signed-off-by: Oliver Pinter <oliver.pntr@gmail.com>
The Giant acquisition here wraps device_probe_and_attach(), which is a bus topology operation. Use the handle that says so. No functional change: bus_topo_lock() is still &Giant today. This file is not referenced by any files* entry, sys/modules Makefile or kernel configuration, and it still includes headers that no longer exist (machine/xen-os.h, machine/hypervisor.h, machine/xenbus.h). It is converted here only so that no bus topology use of Giant is left in the tree; it is untested by construction and is a candidate for removal. Signed-off-by: Oliver Pinter <oliver.pntr@gmail.com>
apei_pcie_handler() calls pci_find_dbsf(), which walks the device tree, so the lock it takes is the bus topology lock. Use the handle that says so, and record why the fatal path deliberately runs without it: the machine is going down and the handler may be running in a context that cannot block. No functional change: bus_topo_lock() is still &Giant today. Signed-off-by: Oliver Pinter <oliver.pntr@gmail.com>
The code has called bus_topo_lock() around DEVICE_SUSPEND and DEVICE_RESUME for some time; only the comment still named Giant. Signed-off-by: Oliver Pinter <oliver.pntr@gmail.com>
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marked this pull request as draft
September 2, 2026 14:16
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