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

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Date:   Thu, 27 Jun 2019 00:33:59 +0530
From:   Kirti Wankhede <kwankhede@...dia.com>
To:     Alex Williamson <alex.williamson@...hat.com>
CC:     <cohuck@...hat.com>, <kvm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mdev: Send uevents around parent device registration



On 6/26/2019 11:35 PM, Alex Williamson wrote:
> On Wed, 26 Jun 2019 23:23:00 +0530
> Kirti Wankhede <kwankhede@...dia.com> wrote:
> 
>> On 6/26/2019 7:57 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>
>>> ---
>>>  drivers/vfio/mdev/mdev_core.c |   10 ++++++++--
>>>  1 file changed, 8 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
>>> index ae23151442cb..ecec2a3b13cb 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)
>>> @@ -196,7 +198,8 @@ int mdev_register_device(struct device *dev, const struct mdev_parent_ops *ops)
>>>  	list_add(&parent->next, &parent_list);
>>>  	mutex_unlock(&parent_list_lock);
>>>  
>>> -	dev_info(dev, "MDEV: Registered\n");
>>> +	kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp);
>>> +  
>>
>> Its good to have udev event, but don't remove debug print from dmesg.
>> Same for unregister.
> 
> Who consumes these?  They seem noisy.  Thanks,
> 

I don't think its noisy, its more of logging purpose. This is seen in
kernel log only when physical device is registered to mdev.

Thanks,
Kirti


> Alex
> 
>>>  	return 0;
>>>  
>>>  add_dev_err:
>>> @@ -220,6 +223,8 @@ 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);
>>> @@ -228,7 +233,6 @@ void mdev_unregister_device(struct device *dev)
>>>  		mutex_unlock(&parent_list_lock);
>>>  		return;
>>>  	}
>>> -	dev_info(dev, "MDEV: Unregistering\n");
>>>  
>>>  	list_del(&parent->next);
>>>  	mutex_unlock(&parent_list_lock);
>>> @@ -243,6 +247,8 @@ void mdev_unregister_device(struct device *dev)
>>>  	up_write(&parent->unreg_sem);
>>>  
>>>  	mdev_put_parent(parent);
>>> +
>>> +	kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp);
>>>  }
>>>  EXPORT_SYMBOL(mdev_unregister_device);
>>>  
>>>   
>