Re: [PATCH 2/2] iommu/vt-d: Use BUG_ON to check NULL value of 'table'

[Baolu Lu <baolu.lu@linux.intel.com>]

On 5/30/23 5:25 PM, Yanfei Xu wrote:
> Checking NULL value of 'table' variable deserves a BUG_ON as the
> following code will trigger a crash by dereferencing the NULL
> 'table' pointer. Crash in advance with BUG_ON to avoid WARN_ON
> plus NULL pointer dereferencing can simplify the crash log.
> 
> Signed-off-by: Yanfei Xu<yanfei.xu@intel.com>
> ---
>   drivers/iommu/intel/iommu.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index e98f1b122b49..8aa3bfdb7f95 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -1944,7 +1944,7 @@ static int domain_context_mapping_one(struct dmar_domain *domain,
>   	if (sm_supported(iommu)) {
>   		unsigned long pds;
>   
> -		WARN_ON(!table);
> +		BUG_ON(!table);

BUG_ON() is not recommended. Perhaps,

		if (!table)
			-ENODEV;

?

Best regards,
baolu