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Date: Wed, 10 Dec 2025 07:54:07 +0100
From: Christoph Hellwig <hch@lst.de>
To: Keith Busch <kbusch@meta.com>
Cc: linux-block@vger.kernel.org, axboe@kernel.dk, hch@lst.de,
	Keith Busch <kbusch@kernel.org>, Sebastian Ott <sebott@redhat.com>
Subject: Re: [PATCH] blk-mq-dma: always initialize dma state
Message-ID: <20251210065407.GA650@lst.de>
References: <20251210064915.3196916-1-kbusch@meta.com>
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On Tue, Dec 09, 2025 at 10:49:15PM -0800, Keith Busch wrote:
> -	if (blk_can_dma_map_iova(req, dma_dev) &&
> -	    dma_iova_try_alloc(dma_dev, state, vec.paddr, total_len))
> +	if (!blk_can_dma_map_iova(req, dma_dev))
> +		memset(state, 0, sizeof(*state));
> +	else if (dma_iova_try_alloc(dma_dev, state, vec.paddr, total_len))
>  		return blk_rq_dma_map_iova(req, dma_dev, state, iter, &vec);

What about just doing the memset unconditionally?  It's just two
64-bit fields so no real overhead, and it gives us a clean slate that
avoid introducing other bugs later on.