linux-kernel - Re: [PATCH v14 08/10] iommu/arm-smmu-v3: Add in-kernel support for NVIDIA Tegra241 (Grace) CMDQV

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Message-ID: <38b6ed33-886f-4ec7-9196-1728f1d8c1b3@stanley.mountain>
Date: Wed, 4 Sep 2024 10:29:26 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Nicolin Chen <nicolinc@...dia.com>
Cc: will@...nel.org, robin.murphy@....com, joro@...tes.org, jgg@...dia.com,
	thierry.reding@...il.com, vdumpa@...dia.com, jonathanh@...dia.com,
	linux-kernel@...r.kernel.org, iommu@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org, linux-tegra@...r.kernel.org
Subject: Re: [PATCH v14 08/10] iommu/arm-smmu-v3: Add in-kernel support for
 NVIDIA Tegra241 (Grace) CMDQV

I was reviewing Smatch warnings:

    drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c:616 tegra241_cmdqv_init_vintf()
    error: Calling ida_alloc_max() with a 'max' argument which is a power of 2. -1 missing?

The problem is that we're calling ida_alloc_max() where max is always zero.

> +static int tegra241_cmdqv_init_vintf(struct tegra241_cmdqv *cmdqv, u16 max_idx,
> +				     struct tegra241_vintf *vintf)
> +{
> +
> +	u16 idx;
> +	int ret;
> +
> +	ret = ida_alloc_max(&cmdqv->vintf_ids, max_idx, GFP_KERNEL);
> +	if (ret < 0)
> +		return ret;
> +	idx = ret;

max_idx is always zero so idx is always zero.

> +
> +	vintf->idx = idx;
> +	vintf->cmdqv = cmdqv;
> +	vintf->base = cmdqv->base + TEGRA241_VINTF(idx);
> +
> +	vintf->lvcmdqs = kcalloc(cmdqv->num_lvcmdqs_per_vintf,
> +				 sizeof(*vintf->lvcmdqs), GFP_KERNEL);
> +	if (!vintf->lvcmdqs) {
> +		ida_free(&cmdqv->vintf_ids, idx);
> +		return -ENOMEM;
> +	}
> +
> +	cmdqv->vintfs[idx] = vintf;

We only use the first element of this array.

> +	return ret;
> +}

We could get rid of the ida_ stuff and change the cmdqv->vintfs[] array to a
pointer.  It would simplify the code.

regards,
dan carpenter