linux-kernel - Re: [PATCH v2] mdev: Send uevents around parent device registration

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Message-ID: <08597ab4-cc37-3973-8927-f1bc430f6185@nvidia.com>
Date:   Mon, 1 Jul 2019 22:43:10 +0530
From:   Kirti Wankhede <kwankhede@...dia.com>
To:     Alex Williamson <alex.williamson@...hat.com>, <cohuck@...hat.com>
CC:     <kvm@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] mdev: Send uevents around parent device registration



On 7/1/2019 8:24 PM, Alex Williamson wrote:
> This allows udev to trigger rules when a parent device is registered
> or unregistered from mdev.
> 
> Signed-off-by: Alex Williamson <alex.williamson@...hat.com>
> ---
> 
> v2: Don't remove the dev_info(), Kirti requested they stay and
>     removing them is only tangential to the goal of this change.
> 

Thanks.


>  drivers/vfio/mdev/mdev_core.c |    8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
> index ae23151442cb..7fb268136c62 100644
> --- a/drivers/vfio/mdev/mdev_core.c
> +++ b/drivers/vfio/mdev/mdev_core.c
> @@ -146,6 +146,8 @@ int mdev_register_device(struct device *dev, const struct mdev_parent_ops *ops)
>  {
>  	int ret;
>  	struct mdev_parent *parent;
> +	char *env_string = "MDEV_STATE=registered";
> +	char *envp[] = { env_string, NULL };
>  
>  	/* check for mandatory ops */
>  	if (!ops || !ops->create || !ops->remove || !ops->supported_type_groups)
> @@ -197,6 +199,8 @@ int mdev_register_device(struct device *dev, const struct mdev_parent_ops *ops)
>  	mutex_unlock(&parent_list_lock);
>  
>  	dev_info(dev, "MDEV: Registered\n");
> +	kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp);
> +
>  	return 0;
>  
>  add_dev_err:
> @@ -220,6 +224,8 @@ EXPORT_SYMBOL(mdev_register_device);
>  void mdev_unregister_device(struct device *dev)
>  {
>  	struct mdev_parent *parent;
> +	char *env_string = "MDEV_STATE=unregistered";
> +	char *envp[] = { env_string, NULL };
>  
>  	mutex_lock(&parent_list_lock);
>  	parent = __find_parent_device(dev);
> @@ -243,6 +249,8 @@ void mdev_unregister_device(struct device *dev)
>  	up_write(&parent->unreg_sem);
>  
>  	mdev_put_parent(parent);
> +
> +	kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp);

mdev_put_parent() calls put_device(dev). If this is the last instance
holding device, then on put_device(dev) dev would get freed.

This event should be before mdev_put_parent()

Thanks,
Kirti

>  }
>  EXPORT_SYMBOL(mdev_unregister_device);
>  
>