Re: [PATCH v4 1/5] vfio/migration: Add debugfs to live migration driver

[Jason Gunthorpe <jgg@nvidia.com>]

On Mon, Dec 05, 2022 at 09:39:29PM +0800, liulongfang wrote:
> On 2022/12/2 23:17, Jason Gunthorpe wrote:
> > On Fri, Dec 02, 2022 at 05:26:21PM +0800, Longfang Liu wrote:
> > 
> >> +static ssize_t vfio_pci_vf_state_read(struct file *filp, char __user *buffer,
> >> +			   size_t count, loff_t *pos)
> >> +{
> > 
> > This would be better to use debugfs_create_devm_seqfile()
> > 
> > Then you can simply use seq_printf()
> >
> 
> The previous debugfs used this method in my patch.
> Is it now recommended to use the interface with "devm" ?

It doesn't matter, the point is not the devm, it is to use the right
helper for the data you want to expose over debugfs 
 
> >> @@ -119,6 +129,8 @@ struct vfio_migration_ops {
> >>  				   enum vfio_device_mig_state *curr_state);
> >>  	int (*migration_get_data_size)(struct vfio_device *device,
> >>  				       unsigned long *stop_copy_length);
> >> +	int (*migration_get_data)(struct vfio_device *device, char *buffer);
> >> +	int (*migration_get_attr)(struct vfio_device *device, char
> >>  				   *buffer);
> > 
> > Still no to passing through debugfs ops, create these files in the
> > driver.
> > 
> 
> If this part is also created and enabled in the device driver, why do we need
> to put this debugfs in the vfio public framework?

To create the directory, and the few actually common files

Jason