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Date: Sat, 4 May 2024 18:50:24 +0100
From: Simon Horman <horms@kernel.org>
To: Shay Drory <shayd@nvidia.com>
Cc: netdev@vger.kernel.org, pabeni@redhat.com, davem@davemloft.net,
	kuba@kernel.org, edumazet@google.com, gregkh@linuxfoundation.org,
	david.m.ertman@intel.com, rafael@kernel.org, ira.weiny@intel.com,
	linux-rdma@vger.kernel.org, leon@kernel.org, tariqt@nvidia.com,
	Parav Pandit <parav@nvidia.com>
Subject: Re: [PATCH 1/2] driver core: auxiliary bus: show auxiliary device
 IRQs
Message-ID: <20240504175024.GI2279@kernel.org>
References: <20240503043104.381938-1-shayd@nvidia.com>
 <20240503043104.381938-2-shayd@nvidia.com>
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In-Reply-To: <20240503043104.381938-2-shayd@nvidia.com>

On Fri, May 03, 2024 at 07:31:03AM +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 file 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 is a 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.
> 
> Additionally, the PCI SFs sometimes share the IRQs with peer SFs. This
> information is also not available to the users. To overcome this
> limitation, each irq sysfs entry shows if irq is exclusive or shared.
> 
> For example:
> $ ls /sys/bus/auxiliary/devices/mlx5_core.sf.1/irqs/
> 50  51  52  53  54  55  56  57  58
> $ cat /sys/bus/auxiliary/devices/mlx5_core.sf.1/irqs/52
> exclusive
> 
> Reviewed-by: Parav Pandit <parav@nvidia.com>
> Signed-off-by: Shay Drory <shayd@nvidia.com>

...

> diff --git a/drivers/base/auxiliary.c b/drivers/base/auxiliary.c

...

> +static int auxiliary_irq_create(int irq)
> +{
> +	refcount_t *ref;
> +	int ret = 0;
> +
> +	mutex_lock(&irqs_lock);
> +	ref = xa_load(&irqs, irq);
> +	if (ref && refcount_inc_not_zero(ref))
> +		goto out;
> +
> +	ref = kzalloc(sizeof(ref), GFP_KERNEL);

Hi Shay,

Should this be sizeof(*ref) ?

Flagged by Coccinelle.

> +	if (!ref) {
> +		ret = -ENOMEM;
> +		goto out;
> +	}
> +
> +	refcount_set(ref, 1);
> +	ret = xa_insert(&irqs, irq, ref, GFP_KERNEL);
> +	if (ret)
> +		kfree(ref);
> +
> +out:
> +	mutex_unlock(&irqs_lock);
> +	return ret;
> +}
> +
> +/**
> + * auxiliary_device_sysfs_irq_add - add a sysfs entry for the given IRQ
> + * @auxdev: auxiliary bus device to add the sysfs entry.
> + * @irq: The associated Linux interrupt number.
> + *
> + * This function should be called after auxiliary device have successfully
> + * received the irq.

It would be nice to include a Return section to this kernel doc.

Flagged by ./scripts/kernel-doc -none -Wall

> + */
> +int auxiliary_device_sysfs_irq_add(struct auxiliary_device *auxdev, int irq)

...