Re: [PATCH 1/2] PCI: Replace pci_dev->is_busmaster with accessors

[Lukas Wunner]

On Sat, Jul 11, 2026 at 05:21:06PM +0200, Maurice Hieronymus wrote:
> `is_busmaster` is one bit of a ~60-bit C bitfield in `struct pci_dev`.
> Bits sharing a bitfield word must not be modified concurrently, but its
> writers take no common lock: `pci_set_master()` can run without the
> device lock (e.g. from runtime PM resume paths), `pci_disable_device()`
> clears the bit, and other bits in the same word are written from
> entirely different contexts, e.g. `broken_parity_status` from sysfs.
> Concurrent read-modify-write cycles of the shared word can then lose
> updates.
> 
> Move `is_busmaster` into a new `flags` bitmap modified with atomic
> bitops and accessed through generated accessor functions, following the
> example of commit a7cc262a1135 ("driver core: Replace dev->offline +
> ->offline_disabled with accessors"). More bitfield flags can follow the
> same pattern later.

We already have the priv_flags member in struct pci_dev,
please use that instead of adding another one for the same purpose.

Thanks,

Lukas