[PATCH] iommu/riscv: Fix signedness bug

[Andrew Jones]

On Thu, Mar 19, 2026 at 01:26:44PM -0500, Ethan Tidmore wrote:
> 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")

This isn't the correct fixes tag. It should be

Fixes: 5c0ebbd3c6c6 ("iommu/riscv: Add RISC-V IOMMU platform device driver")

> Signed-off-by: Ethan Tidmore <ethantidmore06 at 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
>

Otherwise,

Reviewed-by: Andrew Jones <andrew.jones at oss.qualcomm.com>