Re: [Intel-gfx] [PATCH 2/2] drm/i915/gvt: Avoid full proxy f_ops for vgpu_status debug attributes

[Deepak R Varma]

On Tue, Jan 17, 2023 at 02:29:37PM -0500, Rodrigo Vivi wrote:
> On Mon, Jan 16, 2023 at 01:44:46PM +0800, Zhenyu Wang wrote:
> > On 2023.01.10 13:49:57 -0500, Rodrigo Vivi wrote:
> > > On Wed, Jan 11, 2023 at 12:00:12AM +0530, Deepak R Varma wrote:
> > > > Using DEFINE_SIMPLE_ATTRIBUTE macro with the debugfs_create_file()
> > > > function adds the overhead of introducing a proxy file operation
> > > > functions to wrap the original read/write inside file removal protection
> > > > functions. This adds significant overhead in terms of introducing and
> > > > managing the proxy factory file operations structure and function
> > > > wrapping at runtime.
> > > > As a replacement, a combination of DEFINE_DEBUGFS_ATTRIBUTE macro paired
> > > > with debugfs_create_file_unsafe() is suggested to be used instead.  The
> > > > DEFINE_DEBUGFS_ATTRIBUTE utilises debugfs_file_get() and
> > > > debugfs_file_put() wrappers to protect the original read and write
> > > > function calls for the debug attributes. There is no need for any
> > > > runtime proxy file operations to be managed by the debugfs core.
> > > > Following coccicheck make command helped identify this change:
> > > > 
> > > > make coccicheck M=drivers/gpu/drm/i915/ MODE=patch COCCI=./scripts/coccinelle/api/debugfs/debugfs_simple_attr.cocci
> > > > 
> > > > Signed-off-by: Deepak R Varma <drv@xxxxxxxxx>
> > > 
> > > I believe these 2 gvt cases could be done in one patch.
> > > But anyways,
> > > 
> > > Reviewed-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
> > > 
> > > for both patches... and will leave these 2 patches for gvt folks
> > > to apply. Unless they ack and I apply in the drm-intel along with the other ones.
> > >
> > 
> > yeah, they're fine with me, feel free to apply them directly.
> > 
> > Acked-by: Zhenyu Wang <zhenyuw@xxxxxxxxxxxxxxx>
> 
> Unfortunately I got some conflicts when trying to apply on drm-intel-next.
> 
> We probably need a new version, and probably through gvt branches it
> will be easier to handle conflicts if they appear.

Hello Rodrigo,
Sure. I will send in a new version. I am current using linux-next git repo as my
remote origin [tag 20230113]. Are there any specific instruction/location from
where I should access the gvt branch?

Thank you.

> 
> > 
> > thanks!
> > 
> > > > ---
> > > >  drivers/gpu/drm/i915/gvt/debugfs.c | 6 +++---
> > > >  1 file changed, 3 insertions(+), 3 deletions(-)
> > > > 
> > > > diff --git a/drivers/gpu/drm/i915/gvt/debugfs.c b/drivers/gpu/drm/i915/gvt/debugfs.c
> > > > index 03f081c3d9a4..baccbf1761b7 100644
> > > > --- a/drivers/gpu/drm/i915/gvt/debugfs.c
> > > > +++ b/drivers/gpu/drm/i915/gvt/debugfs.c
> > > > @@ -165,7 +165,7 @@ static int vgpu_status_get(void *data, u64 *val)
> > > >  	return 0;
> > > >  }
> > > >  
> > > > -DEFINE_SIMPLE_ATTRIBUTE(vgpu_status_fops, vgpu_status_get, NULL, "0x%llx\n");
> > > > +DEFINE_DEBUGFS_ATTRIBUTE(vgpu_status_fops, vgpu_status_get, NULL, "0x%llx\n");
> > > >  
> > > >  /**
> > > >   * intel_gvt_debugfs_add_vgpu - register debugfs entries for a vGPU
> > > > @@ -182,8 +182,8 @@ void intel_gvt_debugfs_add_vgpu(struct intel_vgpu *vgpu)
> > > >  			    &vgpu_mmio_diff_fops);
> > > >  	debugfs_create_file_unsafe("scan_nonprivbb", 0644, vgpu->debugfs, vgpu,
> > > >  				   &vgpu_scan_nonprivbb_fops);
> > > > -	debugfs_create_file("status", 0644, vgpu->debugfs, vgpu,
> > > > -			    &vgpu_status_fops);
> > > > +	debugfs_create_file_unsafe("status", 0644, vgpu->debugfs, vgpu,
> > > > +				   &vgpu_status_fops);
> > > >  }
> > > >  
> > > >  /**
> > > > -- 
> > > > 2.34.1
> > > > 
> > > > 
> > > > 
> 
>