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

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Message-ID: <aSXV7y49lgA1cWmE@google.com>
Date: Tue, 25 Nov 2025 08:14:39 -0800
From: Brian Norris <briannorris@...omium.org>
To: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: Lukas Wunner <lukas@...ner.de>, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org, linux-pm@...r.kernel.org,
	"Rafael J . Wysocki" <rafael@...nel.org>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Subject: Re: [PATCH v4] PCI/PM: Prevent runtime suspend before devices are
 fully initialized

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@...omium.org>
> Cc: <stable@...r.kernel.org>
> Reviewed-by: Rafael J. Wysocki (Intel) <rafael@...nel.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