Re: [PATCH] kvm: vfio: Convert kvm_vfio_file_add() to use CLASS(fd) and guard(mutex)

[Alex Williamson]

On Fri, 12 Jun 2026 10:15:30 -0600
Alex Williamson <alex@xxxxxxxxxxx> wrote:

> On Sat, 23 May 2026 10:32:42 +0530
> Yash Suthar <yashsuthar983@xxxxxxxxx> wrote:
> 
> > Convert manual fget/fput call to CLASS(fd, f) and
> > mutex_lock/unlock to guard(mutex).
> > 
> > This remove the goto based paths both out_unlock and
> > out_fput.
> > 
> > Signed-off-by: Yash Suthar <yashsuthar983@xxxxxxxxx>
> > ---
> >  virt/kvm/vfio.c | 37 ++++++++++++++-----------------------
> >  1 file changed, 14 insertions(+), 23 deletions(-)  
> 
> Sean already took Carlos' series[1] that mostly 

Sent too soon, [1] mostly handles this, only maybe the CLASS change
remains, if that's still worthwhile on its own.  Thanks,

Alex

[1]https://lore.kernel.org/all/20260313122040.1413091-3-clopez@xxxxxxx/
 
> > diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
> > index 9f9acb66cc1e..bb3694d9c0c4 100644
> > --- a/virt/kvm/vfio.c
> > +++ b/virt/kvm/vfio.c
> > @@ -144,45 +144,36 @@ static int kvm_vfio_file_add(struct kvm_device *dev, unsigned int fd)
> >  {
> >  	struct kvm_vfio *kv = dev->private;
> >  	struct kvm_vfio_file *kvf;
> > -	struct file *filp;
> > -	int ret = 0;
> > +	struct file *file;
> > +	CLASS(fd, f)(fd);
> >  
> > -	filp = fget(fd);
> > -	if (!filp)
> > +	if (fd_empty(f))
> >  		return -EBADF;
> >  
> > +	file = fd_file(f);
> > +
> >  	/* Ensure the FD is a vfio FD. */
> > -	if (!kvm_vfio_file_is_valid(filp)) {
> > -		ret = -EINVAL;
> > -		goto out_fput;
> > -	}
> > +	if (!kvm_vfio_file_is_valid(file))
> > +		return -EINVAL;
> >  
> > -	mutex_lock(&kv->lock);
> > +	guard(mutex)(&kv->lock);
> >  
> >  	list_for_each_entry(kvf, &kv->file_list, node) {
> > -		if (kvf->file == filp) {
> > -			ret = -EEXIST;
> > -			goto out_unlock;
> > -		}
> > +		if (kvf->file == file)
> > +			return -EEXIST;
> >  	}
> >  
> >  	kvf = kzalloc_obj(*kvf, GFP_KERNEL_ACCOUNT);
> > -	if (!kvf) {
> > -		ret = -ENOMEM;
> > -		goto out_unlock;
> > -	}
> > +	if (!kvf)
> > +		return -ENOMEM;
> >  
> > -	kvf->file = get_file(filp);
> > +	kvf->file = get_file(file);
> >  	list_add_tail(&kvf->node, &kv->file_list);
> >  
> >  	kvm_vfio_file_set_kvm(kvf->file, dev->kvm);
> >  	kvm_vfio_update_coherency(dev);
> >  
> > -out_unlock:
> > -	mutex_unlock(&kv->lock);
> > -out_fput:
> > -	fput(filp);
> > -	return ret;
> > +	return 0;
> >  }
> >  
> >  static int kvm_vfio_file_del(struct kvm_device *dev, unsigned int fd)  
>