[PATCH] iommu/riscv: Fix signedness bug

From: Ethan Tidmore <ethantidmore06@gmail.com>
To: Tomasz Jeznach <tjeznach@rivosinc.com>,
	Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
	Paul Walmsley <pjw@kernel.org>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>
Cc: Robin Murphy <robin.murphy@arm.com>,
	Alexandre Ghiti <alex@ghiti.fr>,
	Yaxing Guo <guoyaxing@bosc.ac.cn>,
	Andrew Jones <andrew.jones@oss.qualcomm.com>,
	iommu@lists.linux.dev, linux-riscv@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	Ethan Tidmore <ethantidmore06@gmail.com>
Subject: [PATCH] iommu/riscv: Fix signedness bug
Date: Thu, 19 Mar 2026 13:26:44 -0500	[thread overview]
Message-ID: <20260319182644.1082740-1-ethantidmore06@gmail.com> (raw)

The function platform_irq_count() returns negative error codes and
iommu->irqs_count is an unsigned integer, so the check
(iommu->irqs_count <= 0) is always impossible.

Make the return value of platform_irq_count() be assigned to ret, check
for error, and then assign iommu->irqs_count to ret.

Detected by Smatch:
drivers/iommu/riscv/iommu-platform.c:119 riscv_iommu_platform_probe() warn:
'iommu->irqs_count' unsigned <= 0

Fixes: 7217cee35aadb ("iommu/riscv: Skip IRQ count check when using MSI interrupts")
Signed-off-by: Ethan Tidmore <ethantidmore06@gmail.com>
---
 drivers/iommu/riscv/iommu-platform.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/riscv/iommu-platform.c b/drivers/iommu/riscv/iommu-platform.c
index 8f15b06e8499..399ba8fe1b3e 100644
--- a/drivers/iommu/riscv/iommu-platform.c
+++ b/drivers/iommu/riscv/iommu-platform.c
@@ -115,10 +115,13 @@ static int riscv_iommu_platform_probe(struct platform_device *pdev)
 		fallthrough;
 
 	case RISCV_IOMMU_CAPABILITIES_IGS_WSI:
-		iommu->irqs_count = platform_irq_count(pdev);
-		if (iommu->irqs_count <= 0)
+		ret = platform_irq_count(pdev);
+		if (ret <= 0)
 			return dev_err_probe(dev, -ENODEV,
 					     "no IRQ resources provided\n");
+
+		iommu->irqs_count = ret;
+
 		if (iommu->irqs_count > RISCV_IOMMU_INTR_COUNT)
 			iommu->irqs_count = RISCV_IOMMU_INTR_COUNT;
 
-- 
2.53.0


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