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Subject: Re: [PATCH] iommu/dma: fix incorrect error return on iommu deferred
 attach
To:     Logan Gunthorpe <logang@deltatee.com>,
        <linux-kernel@vger.kernel.org>, <iommu@lists.linux-foundation.org>,
        Christoph Hellwig <hch@lst.de>
CC:     Will Deacon <will@kernel.org>,
        Marshall Midden <marshallmidden@gmail.com>
References: <20211027174757.119755-1-logang@deltatee.com>
From:   John Garry <john.garry@huawei.com>
Message-ID: <0ad0367d-1242-1c41-ad7c-6c4cc4f70983@huawei.com>
Date:   Mon, 1 Nov 2021 09:21:20 +0000
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On 27/10/2021 18:47, Logan Gunthorpe wrote:
> scsi_dma_map() was reporting a failure during boot on an AMD machine
> with the IOMMU enabled.
> 
>    scsi_dma_map failed: request for 36 bytes!
> 
> The issue was tracked down to a mistake in logic: should not return
> an error if iommu_deferred_attach() returns zero.
> 
> Reported-by: Marshall Midden<marshallmidden@gmail.com>
> Fixes: dabb16f67215 ("iommu/dma: return error code from iommu_dma_map_sg()")
> Link:https://lore.kernel.org/all/CAD2CkAWjS8=kKwEEN4cgVNjyFORUibzEiCUA-X+SMtbo0JoMmA@mail.gmail.com
> Signed-off-by: Logan Gunthorpe<logang@deltatee.com>
> Cc: Joerg Roedel<joro@8bytes.org>
> Cc: Will Deacon<will@kernel.org>

Seems reasonable, FWIW:
Reviewed-by: John Garry <john.garry@huawei.com>