From: Christoph Hellwig <hch@lst.de>
To: Atish Patra <atish.patra@wdc.com>
Cc: linux-kernel@vger.kernel.org, Albert Ou <aou@eecs.berkeley.edu>,
Christoph Hellwig <hch@lst.de>,
devicetree@vger.kernel.org, Dmitry Vyukov <dvyukov@google.com>,
Frank Rowand <frowand.list@gmail.com>,
Guo Ren <guoren@linux.alibaba.com>,
iommu@lists.linux-foundation.org,
linux-riscv@lists.infradead.org,
Marek Szyprowski <m.szyprowski@samsung.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Rob Herring <robh+dt@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
Tobias Klauser <tklauser@distanz.ch>
Subject: Re: [RFC 4/5] dma-direct: Allocate dma pages directly if global pool allocation fails
Date: Mon, 26 Jul 2021 09:01:00 +0200 [thread overview]
Message-ID: <20210726070100.GC9035@lst.de> (raw)
In-Reply-To: <20210723214031.3251801-5-atish.patra@wdc.com>
On Fri, Jul 23, 2021 at 02:40:30PM -0700, Atish Patra wrote:
> DMA_GLOBAL_POOL config may be enabled for platforms where global pool is
> not supported because a generic defconfig is expected to boot on different
> platforms. Specifically, some RISC-V platforms may use global pool for
> non-coherent devices while some other platforms are completely coherent.
> However, it is expected that single kernel image must boot on all the
> platforms.
>
> Continue the dma direct allocation if a allocation from global pool failed.
> This indicates that the platform is relying on some other method (direct
> remap) or just have coherent devices.
>
> Signed-off-by: Atish Patra <atish.patra@wdc.com>
> ---
> kernel/dma/direct.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
> index d1d0258ed6d0..984ea776f099 100644
> --- a/kernel/dma/direct.c
> +++ b/kernel/dma/direct.c
> @@ -161,8 +161,11 @@ void *dma_direct_alloc(struct device *dev, size_t size,
> return arch_dma_alloc(dev, size, dma_handle, gfp, attrs);
>
> if (IS_ENABLED(CONFIG_DMA_GLOBAL_POOL) &&
> - !dev_is_dma_coherent(dev))
> - return dma_alloc_from_global_coherent(dev, size, dma_handle);
> + !dev_is_dma_coherent(dev)) {
> + ret = dma_alloc_from_global_coherent(dev, size, dma_handle);
> + if (ret)
> + return ret;
This will now silently return normal non-cache coherent memory when
the global pool allocation fails, and thus is completely broken.
next prev parent reply other threads:[~2021-07-26 7:01 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-23 21:40 [RFC 0/5] Support non-coherent DMA on RISC-V using a global pool Atish Patra
2021-07-23 21:40 ` [RFC 1/5] RISC-V: Implement arch_sync_dma* functions Atish Patra
2021-07-26 6:56 ` Christoph Hellwig
2021-07-26 21:52 ` Atish Patra
2021-09-11 9:37 ` Guo Ren
2021-08-17 1:48 ` Guo Ren
2021-08-17 3:24 ` Atish Patra
2021-08-17 6:28 ` Guo Ren
2021-07-23 21:40 ` [RFC 2/5] of: Move of_dma_get_range to of_address.h Atish Patra
2021-07-23 21:40 ` [RFC 3/5] dma-mapping: Enable global non-coherent pool support for RISC-V Atish Patra
2021-07-25 22:29 ` Rob Herring
2021-07-26 7:00 ` Christoph Hellwig
2021-07-26 22:47 ` Atish Patra
2021-07-27 8:52 ` Christoph Hellwig
2021-08-02 18:22 ` Atish Patra
2021-07-23 21:40 ` [RFC 4/5] dma-direct: Allocate dma pages directly if global pool allocation fails Atish Patra
2021-07-26 7:01 ` Christoph Hellwig [this message]
2021-07-23 21:40 ` [RFC 5/5] RISC-V: Support a new config option for non-coherent DMA Atish Patra
2021-07-29 4:30 ` [RFC 0/5] Support non-coherent DMA on RISC-V using a global pool Palmer Dabbelt
2021-07-29 6:19 ` Atish Patra
2021-08-17 1:37 ` Guo Ren
2021-08-17 3:28 ` Atish Patra
2021-08-17 6:42 ` Guo Ren
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210726070100.GC9035@lst.de \
--to=hch@lst.de \
--cc=aou@eecs.berkeley.edu \
--cc=atish.patra@wdc.com \
--cc=devicetree@vger.kernel.org \
--cc=dvyukov@google.com \
--cc=frowand.list@gmail.com \
--cc=guoren@linux.alibaba.com \
--cc=iommu@lists.linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-riscv@lists.infradead.org \
--cc=m.szyprowski@samsung.com \
--cc=palmer@dabbelt.com \
--cc=paul.walmsley@sifive.com \
--cc=robh+dt@kernel.org \
--cc=robin.murphy@arm.com \
--cc=tklauser@distanz.ch \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).