linux-kernel - Re: [PATCH 4/5] PCI: Add max_vfs in sysfs per pci device where supports

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Message-ID: <20121004141505.GJ9158@phenom.dumpdata.com>
Date:	Thu, 4 Oct 2012 10:15:06 -0400
From:	Konrad Rzeszutek Wilk <konrad@...nel.org>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Bjorn Helgaas <bhelgaas@...gle.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	Don Dutile <ddutile@...hat.com>, yuvalmin@...adcom.com,
	bhutchings@...arflare.com, gregory.v.rose@...el.com,
	davem@...emloft.net--no-chain-reply-to
Subject: Re: [PATCH 4/5] PCI: Add max_vfs in sysfs per pci device where
 supports

On Wed, Oct 03, 2012 at 10:51:34AM -0700, Yinghai Lu wrote:
> only pci device that support sriov will have max_vfs show up in /sys
  ^-Only   ^-devices           ^-SRIOV

> 
> when user set value in /sys, driver ops set_max_vfs will be called to enable
> VF there.

Huh? What value? What are they enabling? Your comment makes it sound as
if setting any value (say '0xdeadbeef') will be called to enable a VF.

I don't think that is what the code does. Can you explain what the
proper values are to be submitted to the SysFS value 'max_vfs' and
what the kernel ought to be doing? Perhaps include a little snippet
from the kernel log so if somebody has a bug they can look at see
what you got and can compare?

Thank you.
> 
> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> ---
>  drivers/pci/pci-sysfs.c |   51 +++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/pci.h     |    1 +
>  2 files changed, 52 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
> index fbbb97f..9b6f409 100644
> --- a/drivers/pci/pci-sysfs.c
> +++ b/drivers/pci/pci-sysfs.c
> @@ -458,6 +458,52 @@ boot_vga_show(struct device *dev, struct device_attribute *attr, char *buf)
>  }
>  struct device_attribute vga_attr = __ATTR_RO(boot_vga);
>  
> +static ssize_t
> +max_vfs_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> +	struct pci_dev *pdev = to_pci_dev(dev);
> +
> +	return sprintf(buf, "%u\n", pdev->max_vfs);
> +}
> +
> +static void max_vfs_callback(struct device *dev)
> +{
> +	struct pci_dev *pdev = to_pci_dev(dev);
> +
> +	mutex_lock(&pci_remove_rescan_mutex);
> +	if (pdev->is_added && dev->driver) {
> +		struct pci_driver *pdrv;
> +
> +		pdrv = to_pci_driver(dev->driver);
> +		if (pdrv->set_max_vfs)
> +			pdrv->set_max_vfs(pdev);
> +
> +	}
> +	mutex_unlock(&pci_remove_rescan_mutex);
> +}
> +static ssize_t
> +max_vfs_store(struct device *dev, struct device_attribute *attr,
> +		 const char *buf, size_t count)
> +{
> +	unsigned long val;
> +	int err;
> +	struct pci_dev *pdev = to_pci_dev(dev);
> +
> +	if (kstrtoul(buf, 0, &val) < 0)
> +		return -EINVAL;
> +
> +	pdev->max_vfs = val;
> +
> +	err = device_schedule_callback(dev, max_vfs_callback);
> +
> +	if (err)
> +		return err;
> +
> +	return count;
> +}
> +struct device_attribute max_vfs_attr =
> +	__ATTR(max_vfs, 0644, max_vfs_show, max_vfs_store);
> +
>  static void
>  pci_config_pm_runtime_get(struct pci_dev *pdev)
>  {
> @@ -1405,6 +1451,7 @@ late_initcall(pci_sysfs_init);
>  
>  static struct attribute *pci_dev_dev_attrs[] = {
>  	&vga_attr.attr,
> +	&max_vfs_attr.attr,
>  	NULL,
>  };
>  
> @@ -1418,6 +1465,10 @@ static umode_t pci_dev_attrs_are_visible(struct kobject *kobj,
>  		if ((pdev->class >> 8) != PCI_CLASS_DISPLAY_VGA)
>  			return 0;
>  
> +	if (a == &max_vfs_attr.attr)
> +		if (!pdev->is_physfn)
> +			return 0;
> +
>  	return a->mode;
>  }
>  
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 7d70a5e..f7423d4 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -335,6 +335,7 @@ struct pci_dev {
>  	unsigned int	broken_intx_masking:1;
>  	unsigned int	io_window_1k:1;	/* Intel P2P bridge 1K I/O windows */
>  	pci_dev_flags_t dev_flags;
> +	unsigned int	max_vfs;
>  	atomic_t	enable_cnt;	/* pci_enable_device has been called */
>  
>  	u32		saved_config_space[16]; /* config space saved at suspend time */
> -- 
> 1.7.7
> 
> --
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