Re: [PATCH v4] PCI/PM: Prevent runtime suspend before devices are fully initialized

Brian Norris
2025-11-25T16:14:43Z

Hi Bjorn,

On Thu, Oct 23, 2025 at 02:09:01PM -0700, Brian Norris wrote:
> Today, it's possible for a PCI device to be created and
> runtime-suspended before it is fully initialized. When that happens, the
> device will remain in D0, but the suspend process may save an
> intermediate version of that device's state -- for example, without
> appropriate BAR configuration. When the device later resumes, we'll
> restore invalid PCI state and the device may not function.
>
> Prevent runtime suspend for PCI devices by deferring pm_runtime_enable()
> until we've fully initialized the device.
[...]
> Link: https://lore.kernel.org/all/20251016155335.1.I60a53c170a8596661883bd2b4ef475155c7aa72b@changeid/
> Signed-off-by: Brian Norris <briannorris@chromium.org>
> Cc: <stable@vger.kernel.org>
> Reviewed-by: Rafael J. Wysocki (Intel) <rafael@kernel.org>
> ---
>
> Changes in v4:
> * Move pm_runtime_set_active() too
>
> Changes in v3:
> * Add Link to initial discussion
> * Add Rafael's Reviewed-by
> * Add lengthier footnotes about forbid vs allow vs sysfs
>
> Changes in v2:
> * Update CC list
> * Rework problem description
> * Update solution: defer pm_runtime_enable(), instead of trying to
> get()/put()
>
> drivers/pci/bus.c | 4 ++++
> drivers/pci/pci.c | 2 --
> 2 files changed, 4 insertions(+), 2 deletions(-)

I'm wondering what the status of this patch is, as the next merge window
is approaching. It fixes a critical bug for me, and it has had plenty of
review.

Thanks,
Brian