Subject: Re: [PATCH net-next v7 1/2] driver core: auxiliary bus: show auxiliary device IRQs

From: Simon Horman <[email-masked]>
Date: Thu, 20 Jun 2024 20:48:34 +0100

On Tue, Jun 18, 2024 at 06:09:01PM +0300, Shay Drory wrote:
> PCI subfunctions (SF) are anchored on the auxiliary bus. PCI physical
> and virtual functions are anchored on the PCI bus. The irq information
> of each such function is visible to users via sysfs directory "msi_irqs"
> containing files for each irq entry. However, for PCI SFs such
> information is unavailable. Due to this users have no visibility on IRQs
> used by the SFs.
> Secondly, an SF can be multi function device supporting rdma, netdevice
> and more. Without irq information at the bus level, the user is unable
> to view or use the affinity of the SF IRQs.
> 
> Hence to match to the equivalent PCI PFs and VFs, add "irqs" directory,
> for supporting auxiliary devices, containing file for each irq entry.
> 
> For example:
> $ ls /sys/bus/auxiliary/devices/mlx5_core.sf.1/irqs/
> 50  51  52  53  54  55  56  57  58
> 
> Reviewed-by: Parav Pandit <[email-masked]>
> Signed-off-by: Shay Drory <[email-masked]>

...

> --- a/include/linux/auxiliary_bus.h
> +++ b/include/linux/auxiliary_bus.h
> @@ -58,6 +58,7 @@
>   *       in
>   * @name: Match name found by the auxiliary device driver,
>   * @id: unique identitier if multiple devices of the same name are exported,
> + * @irqs: irqs xarray contains irq indices which are used by the device,

Hi Shay,

A minor nit from my side: please also add entries for @lock and @dir_exists.

Flagged by kernel-doc -none

>   *
>   * An auxiliary_device represents a part of its parent device's functionality.
>   * It is given a name that, combined with the registering drivers
> @@ -138,7 +139,10 @@
>  struct auxiliary_device {
>  	struct device dev;
>  	const char *name;
> +	struct xarray irqs;
> +	struct mutex lock; /* Protects "irqs" directory creation */
>  	u32 id;
> +	u8 dir_exists:1;
>  };
>  
>  /**

...