Re: [PATCH v3 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

[Hook, Gary]

On 4/13/2018 8:08 PM, Mehta, Sohil wrote:
> On Fri, 2018-04-06 at 08:17 -0500, Gary R Hook wrote:
> >   
> > +
> > +void amd_iommu_debugfs_setup(struct amd_iommu *iommu)
> > +{
> > +	char name[MAX_NAME_LEN + 1];
> > +	struct dentry *d_top;
> > +
> > +	if (!debugfs_initialized())
>
> Probably not needed.

Right.

> > +		return;
> > +
> > +	mutex_lock(&amd_iommu_debugfs_lock);
> > +	if (!amd_iommu_debugfs) {
> > +		d_top = iommu_debugfs_setup();
> > +		if (d_top)
> > +			amd_iommu_debugfs =
> > debugfs_create_dir("amd", d_top);
> > +	}
> > +	mutex_unlock(&amd_iommu_debugfs_lock);
>
>
> You can do the above only once if you iterate over the IOMMUs here
>  Âinstead of doing it inÂamd_iommu_init.

I'm not sure it matters, given the finite number of IOMMUs in a system, 
and the fact that this work is done exactly once. However, removal of a 
lock is fine thing, so I'll move this around.

> > +	if (amd_iommu_debugfs) {
> > +		snprintf(name, MAX_NAME_LEN, "iommu%02d", iommu-
> > > index);
> > +		iommu->debugfs = debugfs_create_dir(name,
> > +						ÂÂÂÂamd_iommu_debugf
> > s);
> > +		if (!iommu->debugfs) {
> > +			debugfs_remove_recursive(amd_iommu_debugfs);
> > +			amd_iommu_debugfs = NULL;
> > +		}
> > +	}
> > +}
>
> -Sohil