linux-kernel - Re: [PATCH v2] driver core: Check drivers

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Message-ID: <20251014200701.GA859701@bhelgaas>
Date: Tue, 14 Oct 2025 15:07:01 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Vincent Liu <vincent.liu@...anix.com>
Cc: gregkh@...uxfoundation.org, dakr@...nel.org,
	linux-kernel@...r.kernel.org, rafael@...nel.org,
	bhelgaas@...gle.com, linux-pci@...r.kernel.org
Subject: Re: [PATCH v2] driver core: Check drivers_autoprobe for all added
 devices

On Mon, Oct 13, 2025 at 07:14:59PM +0100, Vincent Liu wrote:
> When a device is hot-plugged, the drivers_autoprobe sysfs attribute is
> not checked. This means that drivers_autoprobe is not working as
> intended, e.g. hot-plugged PCIe devices will still be autoprobed and
> bound to drivers even with drivers_autoprobe disabled.
> 
> Make sure all devices check drivers_autoprobe by pushing the
> drivers_autoprobe check into device_initial_probe. This will only
> affect devices on the PCI bus for now as device_initial_probe is only
> called by pci_bus_add_device and bus_probe_device (but bus_probe_device
> already checks for autoprobe).

> In particular for the PCI devices, only
> hot-plugged PCIe devices/VFs should be affected as the default value of
> pci/drivers_autoprobe remains 1 and can only be cleared from userland.

I'm not sure what this last sentence is telling us.  Does
"pci/drivers_autoprobe" refer to struct pci_sriov.drivers_autoprobe?
If so, can you elaborate on the connection with struct
subsys_private.drivers_autoprobe, which this patch tests?  I don't see
anything in this patch related to pci_sriov.

As far as I can tell, this patch is generic with respect to
conventional PCI vs PCIe.  If so, I'd use "PCI" everywhere instead of
a mix of PCI and PCIe.

> Any future callers of device_initial_probe will respsect the
> drivers_autoprobe sysfs attribute, but this should be the intended
> purpose of drivers_autoprobe.

Add "()" after function names to make them easily recognizable as
functions.

s/respsect/respect/
s/but this should be the/which is the/  # maybe? not sure what you intend

> Signed-off-by: Vincent Liu <vincent.liu@...anix.com>
> ---
> v1->v2: Change commit subject to include driver core (no code change)
> 	https://lore.kernel.org/20251001151508.1684592-1-vincent.liu@nutanix.com
> ---
>  drivers/base/bus.c |  3 +--
>  drivers/base/dd.c  | 10 +++++++++-
>  2 files changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/base/bus.c b/drivers/base/bus.c
> index 5e75e1bce551..320e155c6be7 100644
> --- a/drivers/base/bus.c
> +++ b/drivers/base/bus.c
> @@ -533,8 +533,7 @@ void bus_probe_device(struct device *dev)
>  	if (!sp)
>  		return;
>  
> -	if (sp->drivers_autoprobe)
> -		device_initial_probe(dev);
> +	device_initial_probe(dev);
>  
>  	mutex_lock(&sp->mutex);
>  	list_for_each_entry(sif, &sp->interfaces, node)
> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index 13ab98e033ea..37fc57e44e54 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -1077,7 +1077,15 @@ EXPORT_SYMBOL_GPL(device_attach);
>  
>  void device_initial_probe(struct device *dev)
>  {
> -	__device_attach(dev, true);
> +	struct subsys_private *sp = bus_to_subsys(dev->bus);
> +
> +	if (!sp)
> +		return;
> +
> +	if (sp->drivers_autoprobe)
> +		__device_attach(dev, true);
> +
> +	subsys_put(sp);
>  }
>  
>  /*
> -- 
> 2.43.7
>