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Date:   Mon, 16 Jan 2023 13:44:46 +0800
From:   Zhenyu Wang <zhenyuw@linux.intel.com>
To:     Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc:     Deepak R Varma <drv@mailo.com>,
        Zhenyu Wang <zhenyuw@linux.intel.com>,
        Zhi Wang <zhi.a.wang@intel.com>,
        Jani Nikula <jani.nikula@linux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
        Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        intel-gvt-dev@lists.freedesktop.org,
        intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org,
        Praveen Kumar <kumarpraveen@linux.microsoft.com>,
        Saurabh Singh Sengar <ssengar@microsoft.com>
Subject: Re: [PATCH 2/2] drm/i915/gvt: Avoid full proxy f_ops for vgpu_status
 debug attributes
Message-ID: <Y8TkTi+/GQwhiMvO@zhen-hp.sh.intel.com>
Reply-To: Zhenyu Wang <zhenyuw@linux.intel.com>
References: <cover.1673375066.git.drv@mailo.com>
 <188df08e0feba0cda2c92145f513dd4e57c6e6cf.1673375066.git.drv@mailo.com>
 <Y72zVXYLVHXuyK05@intel.com>
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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:
> >=20
> > make coccicheck M=3Ddrivers/gpu/drm/i915/ MODE=3Dpatch COCCI=3D./script=
s/coccinelle/api/debugfs/debugfs_simple_attr.cocci
> >=20
> > Signed-off-by: Deepak R Varma <drv@mailo.com>
>=20
> I believe these 2 gvt cases could be done in one patch.
> But anyways,
>=20
> Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
>=20
> 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 oth=
er ones.
>

yeah, they're fine with me, feel free to apply them directly.

Acked-by: Zhenyu Wang <zhenyuw@linux.intel.com>

thanks!

> > ---
> >  drivers/gpu/drm/i915/gvt/debugfs.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> >=20
> > 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;
> >  }
> > =20
> > -DEFINE_SIMPLE_ATTRIBUTE(vgpu_status_fops, vgpu_status_get, NULL, "0x%l=
lx\n");
> > +DEFINE_DEBUGFS_ATTRIBUTE(vgpu_status_fops, vgpu_status_get, NULL, "0x%=
llx\n");
> > =20
> >  /**
> >   * 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, vgp=
u,
> >  				   &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);
> >  }
> > =20
> >  /**
> > --=20
> > 2.34.1
> >=20
> >=20
> >=20

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