Re: [PATCH v2 1/8] iommu/amd: Refactor AMD IOMMU debugfs initial setup

[Srivastava, Dheeraj Kumar]

Hi,

On 11/27/2024 12:42 AM, Bjorn Helgaas wrote:
> On Wed, Nov 06, 2024 at 01:16:32PM +0530, Dheeraj Kumar Srivastava wrote:
> > Rearrange initial setup of AMD IOMMU debugfs to segregate per IOMMU
> > setup and setup which is common for all IOMMUs. This ensures that common
> > debugfs paths (introduced in subsequent patches) are created only once
> > instead of being created for each IOMMU.
> > ...
>
> > -void amd_iommu_debugfs_setup(struct amd_iommu *iommu)
> > +void amd_iommu_debugfs_setup(void)
> >   {
> > +	struct amd_iommu *iommu;
> >   	char name[MAX_NAME_LEN + 1];
> >   
> > -	mutex_lock(&amd_iommu_debugfs_lock);
> > -	if (!amd_iommu_debugfs)
> > -		amd_iommu_debugfs = debugfs_create_dir("amd",
> > -						       iommu_debugfs_dir);
> > -	mutex_unlock(&amd_iommu_debugfs_lock);
> > +	amd_iommu_debugfs = debugfs_create_dir("amd", iommu_debugfs_dir);
> >   
> > -	snprintf(name, MAX_NAME_LEN, "iommu%02d", iommu->index);
> > -	iommu->debugfs = debugfs_create_dir(name, amd_iommu_debugfs);
> > +	for_each_iommu(iommu) {
> > +		snprintf(name, MAX_NAME_LEN, "iommu%02d", iommu->index);
> > +		iommu->debugfs = debugfs_create_dir(name, amd_iommu_debugfs);
> > +	}
>
> Doing this setup with for_each_iommu() precludes any hot-add of
> IOMMUs, but I guess there's no indication of hotplug support anyway
> given all the uses of for_each_iommu() in init_iommu_all(),
> amd_iommu_init_pci(), amd_iommu_enable_interrupts(), etc.

Yeah and here i don't see any concerns with the approach for now. Please 
do let me know if you have a better way to do this.

Thanks
Dheeraj

> >   }
> > diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
> > index 43131c3a2172..d78dc96bbec3 100644
> > --- a/drivers/iommu/amd/init.c
> > +++ b/drivers/iommu/amd/init.c
> > @@ -3377,7 +3377,6 @@ int amd_iommu_enable_faulting(unsigned int cpu)
> >    */
> >   static int __init amd_iommu_init(void)
> >   {
> > -	struct amd_iommu *iommu;
> >   	int ret;
> >   
> >   	ret = iommu_go_to_state(IOMMU_INITIALIZED);
> > @@ -3391,8 +3390,8 @@ static int __init amd_iommu_init(void)
> >   	}
> >   #endif
> >   
> > -	for_each_iommu(iommu)
> > -		amd_iommu_debugfs_setup(iommu);
> > +	if (!ret)
> > +		amd_iommu_debugfs_setup();
> >   
> >   	return ret;
> >   }
> > --
> > 2.25.1