Re: [PATCH 4/4] drm/i915: add i915_error_state sysfs entry

[Daniel Vetter <daniel@ffwll.ch>]

On Thu, Jun 06, 2013 at 03:18:42PM +0300, Mika Kuoppala wrote:
> As getting error state doesn't anymore require big kmallocs,
> make error state accessible also from sysfs.
> 
> Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_sysfs.c |   49 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 49 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_sysfs.c b/drivers/gpu/drm/i915/i915_sysfs.c
> index 6875b56..d4c754b 100644
> --- a/drivers/gpu/drm/i915/i915_sysfs.c
> +++ b/drivers/gpu/drm/i915/i915_sysfs.c
> @@ -409,6 +409,49 @@ static const struct attribute *gen6_attrs[] = {
>  	NULL,
>  };
>  
> +static ssize_t error_state_read(struct file *filp, struct kobject *kobj,
> +				struct bin_attribute *attr, char *buf,
> +				loff_t off, size_t count)
> +{
> +
> +	struct device *kdev = container_of(kobj, struct device, kobj);
> +	struct drm_minor *minor = container_of(kdev, struct drm_minor, kdev);
> +	struct drm_device *dev = minor->dev;
> +	struct i915_error_state_file_priv error_priv;
> +	struct drm_i915_error_state_buf error_str;
> +	ssize_t ret_count = 0;
> +	int ret;
> +
> +	memset(&error_priv, 0, sizeof(error_priv));
> +
> +	ret = i915_error_state_buf_init(&error_str, count, off);
> +	if (ret)
> +		return ret;
> +
> +	error_priv.dev = dev;
> +	i915_error_state_get(dev, &error_priv);
> +
> +	ret = i915_error_state_to_str(&error_str, &error_priv);
> +	if (ret)
> +		goto out;
> +
> +	ret_count = count < error_str.bytes ? count : error_str.bytes;
> +
> +	memcpy(buf, error_str.buf, ret_count);
> +out:
> +	i915_error_state_buf_release(&error_str);
> +	i915_error_state_put(&error_priv);
> +
> +	return ret ?: ret_count;
> +}
> +
> +static struct bin_attribute error_state_attr = {
> +	.attr.name = "i915_error_state",
> +	.attr.mode = 0444,

Error state could easily leak sensitive information, so I think we should
only allow root to read it. Also maybe a new name for it, i915_ is kinda
meh ... I vote for gpu_error_state.
-Daniel

> +	.size = 0,
> +	.read = error_state_read,
> +};
> +
>  void i915_setup_sysfs(struct drm_device *dev)
>  {
>  	int ret;
> @@ -432,10 +475,16 @@ void i915_setup_sysfs(struct drm_device *dev)
>  		if (ret)
>  			DRM_ERROR("gen6 sysfs setup failed\n");
>  	}
> +
> +	ret = sysfs_create_bin_file(&dev->primary->kdev.kobj,
> +				    &error_state_attr);
> +	if (ret)
> +		DRM_ERROR("error_state sysfs setup failed\n");
>  }
>  
>  void i915_teardown_sysfs(struct drm_device *dev)
>  {
> +	sysfs_remove_bin_file(&dev->primary->kdev.kobj, &error_state_attr);
>  	sysfs_remove_files(&dev->primary->kdev.kobj, gen6_attrs);
>  	device_remove_bin_file(&dev->primary->kdev,  &dpf_attrs);
>  #ifdef CONFIG_PM
> -- 
> 1.7.9.5
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch