Re: [PATCH v2 07/23] dmaengine: sdxi: Allocate administrative context

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Incorrect error check for `dma_pool_zalloc()` allocation using the DMA handle instead of the virtual address.
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commit 67ceee55512586a3fbe30b9f642ed7c90819e736
Author: Nathan Lynch <nathan.lynch@amd.com>

dmaengine: sdxi: Allocate administrative context

This commit creates the control structure hierarchy in memory for the
per-function administrative context. It uses devres to queue the cleanup
since the admin context is a device-scope resource.

> diff --git a/drivers/dma/sdxi/context.c b/drivers/dma/sdxi/context.c
> new file mode 100644
> index 0000000000000..27821cfaf0311
> --- /dev/null
> +++ b/drivers/dma/sdxi/context.c

[ ... ]

> +/* Allocate a context and its control structure hierarchy in memory. */
> +static struct sdxi_cxt *sdxi_alloc_cxt(struct sdxi_dev *sdxi)
> +{

[ ... ]

> +	cxt->cxt_ctl = dma_pool_zalloc(sdxi->cxt_ctl_pool, GFP_KERNEL,
> +				       &cxt->cxt_ctl_dma);
> +	if (!cxt->cxt_ctl_dma)
> +		return NULL;

Could this incorrectly treat a valid allocation as a failure?

A DMA handle of 0 is a valid DMA address on many hardware platforms and
IOMMU configurations. If dma_pool_zalloc() succeeds and returns a DMA
address of 0, checking the DMA handle might falsely trigger this error
path and return NULL.

Should this check the returned virtual address (!cxt->cxt_ctl) instead,
similar to how the subsequent cxt_sts and write_index allocations are
validated?

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Sashiko AI review · https://sashiko.dev/#/patchset/20260511-sdxi-base-v2-0-889cfed17e3f@amd.com?part=7