Re: [PATCH V4 1/3] driver core: mark device as irq affinity managed if any irq is managed

From: John Garry <john.garry@huawei.com>
To: Ming Lei <ming.lei@redhat.com>, Jens Axboe <axboe@kernel.dk>,
	"Christoph Hellwig" <hch@lst.de>, <linux-block@vger.kernel.org>,
	<linux-nvme@lists.infradead.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Bjorn Helgaas <bhelgaas@google.com>, <linux-pci@vger.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Sagi Grimberg <sagi@grimberg.me>, Daniel Wagner <dwagner@suse.de>,
	Wen Xiong <wenxiong@us.ibm.com>, "Hannes Reinecke" <hare@suse.de>,
	Keith Busch <kbusch@kernel.org>
Subject: Re: [PATCH V4 1/3] driver core: mark device as irq affinity managed if any irq is managed
Date: Mon, 19 Jul 2021 08:51:22 +0100	[thread overview]
Message-ID: <5e534fdc-909e-39b2-521d-31f643a10558@huawei.com> (raw)
In-Reply-To: <20210715120844.636968-2-ming.lei@redhat.com>

On 15/07/2021 13:08, Ming Lei wrote:
> irq vector allocation with managed affinity may be used by driver, and
> blk-mq needs this info because managed irq will be shutdown when all
> CPUs in the affinity mask are offline.
> 
> The info of using managed irq is often produced by drivers(pci subsystem,
> platform device, ...), and it is consumed by blk-mq, so different subsystems
> are involved in this info flow
> 
> Address this issue by adding one field of .irq_affinity_managed into
> 'struct device'.
> 
> Suggested-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Ming Lei <ming.lei@redhat.com>

Did you consider that for PCI device we effectively have this info already:

bool dev_has_managed_msi_irq(struct device *dev)
{
	struct msi_desc *desc;

	list_for_each_entry(desc, dev_to_msi_list(dev), list) {
		if (desc->affinity && desc->affinity->is_managed)
			return true;
	}

	return false;
}

Thanks,
John

> ---
>   drivers/base/platform.c | 7 +++++++
>   drivers/pci/msi.c       | 3 +++
>   include/linux/device.h  | 1 +
>   3 files changed, 11 insertions(+)
> 
> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
> index 8640578f45e9..d28cb91d5cf9 100644
> --- a/drivers/base/platform.c
> +++ b/drivers/base/platform.c
> @@ -388,6 +388,13 @@ int devm_platform_get_irqs_affinity(struct platform_device *dev,
>   				ptr->irq[i], ret);
>   			goto err_free_desc;
>   		}
> +
> +		/*
> +		 * mark the device as irq affinity managed if any irq affinity
> +		 * descriptor is managed
> +		 */
> +		if (desc[i].is_managed)
> +			dev->dev.irq_affinity_managed = true;
>   	}
>   
>   	devres_add(&dev->dev, ptr);
> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
> index 3d6db20d1b2b..7ddec90b711d 100644
> --- a/drivers/pci/msi.c
> +++ b/drivers/pci/msi.c
> @@ -1197,6 +1197,7 @@ int pci_alloc_irq_vectors_affinity(struct pci_dev *dev, unsigned int min_vecs,
>   	if (flags & PCI_IRQ_AFFINITY) {
>   		if (!affd)
>   			affd = &msi_default_affd;
> +		dev->dev.irq_affinity_managed = true;
>   	} else {
>   		if (WARN_ON(affd))
>   			affd = NULL;
> @@ -1215,6 +1216,8 @@ int pci_alloc_irq_vectors_affinity(struct pci_dev *dev, unsigned int min_vecs,
>   			return nvecs;
>   	}
>   
> +	dev->dev.irq_affinity_managed = false;
> +
>   	/* use legacy IRQ if allowed */
>   	if (flags & PCI_IRQ_LEGACY) {
>   		if (min_vecs == 1 && dev->irq) {
> diff --git a/include/linux/device.h b/include/linux/device.h
> index 59940f1744c1..9ec6e671279e 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -569,6 +569,7 @@ struct device {
>   #ifdef CONFIG_DMA_OPS_BYPASS
>   	bool			dma_ops_bypass : 1;
>   #endif
> +	bool			irq_affinity_managed : 1;
>   };
>   
>   /**
> 