From: Christoph Hellwig <hch@lst.de>
To: "Ionut Nechita (Wind River)" <ionut.nechita@windriver.com>
Cc: m.szyprowski@samsung.com, kbusch@kernel.org, axboe@kernel.dk,
hch@lst.de, sagi@grimberg.me, robin.murphy@arm.com,
martin.petersen@oracle.com, damien.lemoal@opensource.wdc.com,
john.g.garry@oracle.com, ahuang12@lenovo.com,
iommu@lists.linux.dev, linux-nvme@lists.infradead.org,
linux-kernel@vger.kernel.org, stable@vger.kernel.org,
ionut_n2001@yahoo.com, sunlightlinux@gmail.com
Subject: Re: [PATCH v1 2/2] nvme-pci: handle dma_opt_mapping_size() returning 0
Date: Tue, 17 Mar 2026 15:14:42 +0100 [thread overview]
Message-ID: <20260317141442.GA3539@lst.de> (raw)
In-Reply-To: <20260316203956.64515-3-ionut.nechita@windriver.com>
On Mon, Mar 16, 2026 at 10:39:56PM +0200, Ionut Nechita (Wind River) wrote:
> From: Ionut Nechita <ionut.nechita@windriver.com>
>
> After the previous commit, dma_opt_mapping_size() returns 0 when no DMA
> backend provides an optimal mapping size hint (e.g. IOMMU in passthrough
> mode with no ops->opt_mapping_size callback).
>
> The NVMe PCI driver used min_t(u32, NVME_MAX_BYTES >> SECTOR_SHIFT,
> dma_opt_mapping_size() >> 9) to cap max_hw_sectors. With a 0 return
> value this would set max_hw_sectors to 0, which is invalid.
... which means that if you want to change it, you need to combine
both patches into one to not create a regression.
next prev parent reply other threads:[~2026-03-17 14:14 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-16 20:39 [PATCH v1 0/2] dma: fix dma_opt_mapping_size() returning bogus value when no backend hint exists Ionut Nechita (Wind River)
2026-03-16 20:39 ` [PATCH v1 1/2] dma: return 0 from dma_opt_mapping_size() when no real " Ionut Nechita (Wind River)
2026-03-17 9:43 ` Robin Murphy
2026-03-17 14:19 ` Christoph Hellwig
2026-03-16 20:39 ` [PATCH v1 2/2] nvme-pci: handle dma_opt_mapping_size() returning 0 Ionut Nechita (Wind River)
2026-03-16 21:21 ` Damien Le Moal
2026-03-17 8:55 ` John Garry
2026-03-17 14:14 ` Christoph Hellwig [this message]
2026-03-17 9:11 ` [PATCH v1 0/2] dma: fix dma_opt_mapping_size() returning bogus value when no backend hint exists John Garry
2026-03-17 9:18 ` Damien Le Moal
2026-03-17 14:36 ` Christoph Hellwig
2026-03-17 15:18 ` John Garry
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