From: Christoph Hellwig <hch@lst.de>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: "Christian König" <christian.koenig@amd.com>,
"Chris Wilson" <chris@chris-wilson.co.uk>,
"Michel Dänzer" <michel@daenzer.net>,
"Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
"Christoph Hellwig" <hch@lst.de>,
iommu@lists.linux-foundation.org,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
dri-devel <dri-devel@lists.freedesktop.org>
Subject: Re: [PATCH] swiotlb: Fix inversed DMA_ATTR_NO_WARN test
Date: Wed, 2 May 2018 14:41:51 +0200 [thread overview]
Message-ID: <20180502124151.GA22857@lst.de> (raw)
In-Reply-To: <CAKMK7uH2+v3_UUqXdCjz_8=H4VRt1zB+dgE99PuuPqd+XM2=-w@mail.gmail.com>
On Wed, May 02, 2018 at 02:18:56PM +0200, Daniel Vetter wrote:
> Other dma-api backends like cma just shut up when __GFP_NOWARN is
> passed. And afaiui Christoph Hellwig has plans to nuke the DMA_ATTR
> stuff (or at least clean it up) - should we just remove
> DMA_ATTR_NO_WARN and instead only look at __GFP_NOWARN?
No. __GFP_NOWARN (and gfp_t flags in general) are the wrong interface
for dma allocations and just cause problems. I actually plan to
get rid of the gfp_t argument in dma_alloc_attrs sooner, and only
allow either GFP_KERNEL or GFP_DMA passed in dma_alloc_coherent.
> Or maybe we should at least enforce that both or none are set, for
> consistency for now?
The interface should be DMA_ATTR_NO_WARN. __GFP_NOWARN in this
context was never documented, and just slipped in.
next prev parent reply other threads:[~2018-05-02 12:39 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-01 13:24 [PATCH] swiotlb: Fix inversed DMA_ATTR_NO_WARN test Michel Dänzer
2018-05-02 9:49 ` Christian König
2018-05-02 12:18 ` Daniel Vetter
2018-05-02 12:41 ` Christoph Hellwig [this message]
2018-05-02 14:31 ` Michel Dänzer
2018-05-02 16:21 ` Christoph Hellwig
2018-05-02 16:59 ` Michel Dänzer
2018-05-22 13:13 ` Christian König
2018-05-25 8:41 ` Christoph Hellwig
2018-05-25 8:41 ` Michel Dänzer
2018-05-02 12:42 ` Christoph Hellwig
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