[PATCH] drm/i915/gvt: use DEFINE_DEBUGFS_ATTRIBUTE with debugfs_create_file_unsafe()

[PATCH] drm/i915/gvt: use DEFINE_DEBUGFS_ATTRIBUTE with debugfs_create_file_unsafe()

[Deepak R Varma]

Using DEFINE_DEBUGFS_ATTRIBUTE macro with debugfs_create_file_unsafe()
function in place of the debugfs_create_file() function will make the
file operation struct "reset" aware of the file's lifetime. Additional
details here: https://lists.archive.carbon60.com/linux/kernel/2369498

Issue reported by Coccinelle script:
scripts/coccinelle/api/debugfs/debugfs_simple_attr.cocci

Signed-off-by: Deepak R Varma <mh12gx2825@gmail.com>
---
Please Note: This is a Outreachy project task patch.

 drivers/gpu/drm/i915/gvt/debugfs.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/gvt/debugfs.c b/drivers/gpu/drm/i915/gvt/debugfs.c
index 62e6a14ad58e..18adfa2d5f5b 100644
--- a/drivers/gpu/drm/i915/gvt/debugfs.c
+++ b/drivers/gpu/drm/i915/gvt/debugfs.c
@@ -147,9 +147,8 @@ vgpu_scan_nonprivbb_set(void *data, u64 val)
 	return 0;
 }
 
-DEFINE_SIMPLE_ATTRIBUTE(vgpu_scan_nonprivbb_fops,
-			vgpu_scan_nonprivbb_get, vgpu_scan_nonprivbb_set,
-			"0x%llx\n");
+DEFINE_DEBUGFS_ATTRIBUTE(vgpu_scan_nonprivbb_fops, vgpu_scan_nonprivbb_get,
+			 vgpu_scan_nonprivbb_set, "0x%llx\n");
 
 /**
  * intel_gvt_debugfs_add_vgpu - register debugfs entries for a vGPU
@@ -165,8 +164,8 @@ void intel_gvt_debugfs_add_vgpu(struct intel_vgpu *vgpu)
 	debugfs_create_bool("active", 0444, vgpu->debugfs, &vgpu->active);
 	debugfs_create_file("mmio_diff", 0444, vgpu->debugfs, vgpu,
 			    &vgpu_mmio_diff_fops);
-	debugfs_create_file("scan_nonprivbb", 0644, vgpu->debugfs, vgpu,
-			    &vgpu_scan_nonprivbb_fops);
+	debugfs_create_file_unsafe("scan_nonprivbb", 0644, vgpu->debugfs, vgpu,
+				   &vgpu_scan_nonprivbb_fops);
 }
 
 /**
-- 
2.25.1

Re: [PATCH] drm/i915/gvt: use DEFINE_DEBUGFS_ATTRIBUTE with debugfs_create_file_unsafe()

[Jani Nikula]

On Fri, 30 Oct 2020, Deepak R Varma <mh12gx2825@gmail.com> wrote:
> Using DEFINE_DEBUGFS_ATTRIBUTE macro with debugfs_create_file_unsafe()
> function in place of the debugfs_create_file() function will make the
> file operation struct "reset" aware of the file's lifetime. Additional
> details here: https://lists.archive.carbon60.com/linux/kernel/2369498

Please describe what the functional impact is in the commit message. I
don't understand what 'make the file operation struct "reset" aware of
the file's lifetime' means here.

For referencing LKML posts, please prefer https://lore.kernel.org/.

For referencing commits already in the kernel, please prefer the format
c64688081490 ("debugfs: add support for self-protecting attribute file
fops").


BR,
Jani.

>
> Issue reported by Coccinelle script:
> scripts/coccinelle/api/debugfs/debugfs_simple_attr.cocci
>
> Signed-off-by: Deepak R Varma <mh12gx2825@gmail.com>
> ---
> Please Note: This is a Outreachy project task patch.
>
>  drivers/gpu/drm/i915/gvt/debugfs.c | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gvt/debugfs.c b/drivers/gpu/drm/i915/gvt/debugfs.c
> index 62e6a14ad58e..18adfa2d5f5b 100644
> --- a/drivers/gpu/drm/i915/gvt/debugfs.c
> +++ b/drivers/gpu/drm/i915/gvt/debugfs.c
> @@ -147,9 +147,8 @@ vgpu_scan_nonprivbb_set(void *data, u64 val)
>  	return 0;
>  }
>  
> -DEFINE_SIMPLE_ATTRIBUTE(vgpu_scan_nonprivbb_fops,
> -			vgpu_scan_nonprivbb_get, vgpu_scan_nonprivbb_set,
> -			"0x%llx\n");
> +DEFINE_DEBUGFS_ATTRIBUTE(vgpu_scan_nonprivbb_fops, vgpu_scan_nonprivbb_get,
> +			 vgpu_scan_nonprivbb_set, "0x%llx\n");
>  
>  /**
>   * intel_gvt_debugfs_add_vgpu - register debugfs entries for a vGPU
> @@ -165,8 +164,8 @@ void intel_gvt_debugfs_add_vgpu(struct intel_vgpu *vgpu)
>  	debugfs_create_bool("active", 0444, vgpu->debugfs, &vgpu->active);
>  	debugfs_create_file("mmio_diff", 0444, vgpu->debugfs, vgpu,
>  			    &vgpu_mmio_diff_fops);
> -	debugfs_create_file("scan_nonprivbb", 0644, vgpu->debugfs, vgpu,
> -			    &vgpu_scan_nonprivbb_fops);
> +	debugfs_create_file_unsafe("scan_nonprivbb", 0644, vgpu->debugfs, vgpu,
> +				   &vgpu_scan_nonprivbb_fops);
>  }
>  
>  /**

-- 
Jani Nikula, Intel Open Source Graphics Center