[PATCH] iommu/amd: Drop incorrect NULL check for iommu in alloc_irq_table()

[PATCH] iommu/amd: Drop incorrect NULL check for iommu in alloc_irq_table()

[Rakuram Eswaran]

alloc_irq_table() contains a conditional check for a NULL iommu pointer
when computing the NUMA node, but the function dereferences iommu
in multiple places afterwards.

All callers ensure that a valid iommu pointer is passed in, and a NULL
iommu is not expected by the current callers. Remove the incorrect
NULL check to make the assumptions consistent and address the Smatch
warning.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202512191724.meqJENXe-lkp@intel.com/
Signed-off-by: Rakuram Eswaran <rakuram.e96@gmail.com>
---
Testing note:
Compile tested only.

Build and Analysis:
This patch was compiled against the configuration file reported by
0day CI in the above link (config: x86_64-randconfig-r073-20251215)
using gcc version 15.2.0 (Ubuntu 15.2.0-4ubuntu4).

Static analysis was performed with Smatch to ensure the reported warning
no longer reproduces after applying this fix.

Command using for Smatch testing:
~/project/smatch/smatch_scripts/kchecker ./drivers/iommu/amd/iommu.c

 drivers/iommu/amd/iommu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 075125f0f52b..611e3ccc93d1 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -3240,7 +3240,7 @@ static struct irq_remap_table *alloc_irq_table(struct amd_iommu *iommu,
 	struct irq_remap_table *new_table = NULL;
 	struct amd_iommu_pci_seg *pci_seg;
 	unsigned long flags;
-	int nid = iommu && iommu->dev ? dev_to_node(&iommu->dev->dev) : NUMA_NO_NODE;
+	int nid = iommu->dev ? dev_to_node(&iommu->dev->dev) : NUMA_NO_NODE;
 	u16 alias;
 
 	spin_lock_irqsave(&iommu_table_lock, flags);
-- 
2.51.0

Re: [PATCH] iommu/amd: Drop incorrect NULL check for iommu in alloc_irq_table()

[Ankit Soni]

On Mon, Dec 22, 2025 at 10:40:08PM +0530, Rakuram Eswaran wrote:
> alloc_irq_table() contains a conditional check for a NULL iommu pointer
> when computing the NUMA node, but the function dereferences iommu
> in multiple places afterwards.
> 
> All callers ensure that a valid iommu pointer is passed in, and a NULL
> iommu is not expected by the current callers. Remove the incorrect
> NULL check to make the assumptions consistent and address the Smatch
> warning.
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
> Closes: https://lore.kernel.org/r/202512191724.meqJENXe-lkp@intel.com/
> Signed-off-by: Rakuram Eswaran <rakuram.e96@gmail.com>

Looks good to me.
Reviewed-by: Ankit Soni <Ankit.Soni@amd.com>

> ---
> Testing note:
> Compile tested only.
> 
> Build and Analysis:
> This patch was compiled against the configuration file reported by
> 0day CI in the above link (config: x86_64-randconfig-r073-20251215)
> using gcc version 15.2.0 (Ubuntu 15.2.0-4ubuntu4).
> 
> Static analysis was performed with Smatch to ensure the reported warning
> no longer reproduces after applying this fix.
> 
> Command using for Smatch testing:
> ~/project/smatch/smatch_scripts/kchecker ./drivers/iommu/amd/iommu.c
> 
>  drivers/iommu/amd/iommu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
> index 075125f0f52b..611e3ccc93d1 100644
> --- a/drivers/iommu/amd/iommu.c
> +++ b/drivers/iommu/amd/iommu.c
> @@ -3240,7 +3240,7 @@ static struct irq_remap_table *alloc_irq_table(struct amd_iommu *iommu,
>  	struct irq_remap_table *new_table = NULL;
>  	struct amd_iommu_pci_seg *pci_seg;
>  	unsigned long flags;
> -	int nid = iommu && iommu->dev ? dev_to_node(&iommu->dev->dev) : NUMA_NO_NODE;
> +	int nid = iommu->dev ? dev_to_node(&iommu->dev->dev) : NUMA_NO_NODE;
>  	u16 alias;
>  
>  	spin_lock_irqsave(&iommu_table_lock, flags);
> -- 
> 2.51.0
> 

Re: [PATCH] iommu/amd: Drop incorrect NULL check for iommu in alloc_irq_table()

[Jörg Rödel]

On Mon, Dec 22, 2025 at 10:40:08PM +0530, Rakuram Eswaran wrote:
>  drivers/iommu/amd/iommu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Applied, thanks.