linux-kernel - [PATCH] iommu/amd: Drop incorrect NULL check for iommu in alloc_irq

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Message-ID: <20251222171009.44670-1-rakuram.e96@gmail.com>
Date: Mon, 22 Dec 2025 22:40:08 +0530
From: Rakuram Eswaran <rakuram.e96@...il.com>
To: joro@...tes.org,
	will@...nel.org,
	suravee.suthikulpanit@....com,
	robin.murphy@....com,
	iommu@...ts.linux.dev
Cc: dan.carpenter@...aro.org,
	lkp@...el.com,
	linux-kernel@...r.kernel.org,
	rakuram.e96@...il.com
Subject: [PATCH] iommu/amd: Drop incorrect NULL check for iommu in alloc_irq_table()

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@...el.com>
Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
Closes: https://lore.kernel.org/r/202512191724.meqJENXe-lkp@intel.com/
Signed-off-by: Rakuram Eswaran <rakuram.e96@...il.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