Re: [PATCH v1 1/6] iommu/dmar: Fix crash on boot when DMAR is disabled

[Andy Shevchenko <andriy.shevchenko-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>]

On Wed, 2017-02-15 at 16:42 +0200, Andy Shevchenko wrote:
> By default CONFIG_INTEL_IOMMU_DEFAULT_ON is not set and thus
> dmar_disabled variable is set.
> 
> Intel IOMMU driver based on above doesn't set intel_iommu_enabled
> variable.
> 
> The commit b0119e870837 ("iommu: Introduce new 'struct iommu_device'")
> mistakenly assumes it never happens and tries to unregister not ever
> registered resources, which crashes the kernel at boot time:
> 
> 	BUG: unable to handle kernel NULL pointer dereference at
> 0000000000000008
> 	IP: iommu_device_unregister+0x31/0x60
> 
> Make unregister procedure conditional in free_iommu().

Joerg, it looks like bug is still present. Can we get the fix merged?
Or do you have better ideas?

> 
> Fixes: b0119e870837 ("iommu: Introduce new 'struct iommu_device'")
> Cc: Joerg Roedel <jroedel@suse.de>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
>  drivers/iommu/dmar.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
> index d9c0decfc91a..36e3f430d265 100644
> --- a/drivers/iommu/dmar.c
> +++ b/drivers/iommu/dmar.c
> @@ -1108,8 +1108,10 @@ static int alloc_iommu(struct dmar_drhd_unit
> *drhd)
>  
>  static void free_iommu(struct intel_iommu *iommu)
>  {
> -	iommu_device_sysfs_remove(&iommu->iommu);
> -	iommu_device_unregister(&iommu->iommu);
> +	if (intel_iommu_enabled) {
> +		iommu_device_unregister(&iommu->iommu);
> +		iommu_device_sysfs_remove(&iommu->iommu);
> +	}
>  
>  	if (iommu->irq) {
>  		if (iommu->pr_irq) {

-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy
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