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Message-ID: <CAH1PCMZL-AGJE6PXrpyShYEMFkvoi-Ajzd_Az0ma75QWZFaROQ@mail.gmail.com>
Date: Mon, 18 Aug 2025 20:27:21 +0800
From: Guodong Xu <guodong@...cstar.com>
To: Dan Carpenter <dan.carpenter@...aro.org>
Cc: oe-kbuild@...ts.linux.dev, Vinod Koul <vkoul@...nel.org>,
Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk@...nel.org>, Conor Dooley <conor+dt@...nel.org>,
Yixun Lan <dlan@...too.org>, Philipp Zabel <p.zabel@...gutronix.de>,
Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>, Alexandre Ghiti <alex@...ti.fr>, duje@...emihanovic.xyz,
lkp@...el.com, oe-kbuild-all@...ts.linux.dev, Alex Elder <elder@...cstar.com>,
Vivian Wang <wangruikang@...as.ac.cn>, dmaengine@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-riscv@...ts.infradead.org, spacemit@...ts.linux.dev,
Troy Mitchell <troy.mitchell@...ux.spacemit.com>
Subject: Re: [PATCH v4 4/8] dmaengine: mmp_pdma: Add operations structure for
controller abstraction
Hi, Dan
On Mon, Aug 18, 2025 at 3:17 PM Dan Carpenter <dan.carpenter@...aro.org> wrote:
>
> Hi Guodong,
>
> kernel test robot noticed the following build warnings:
>
> url: https://github.com/intel-lab-lkp/linux/commits/Guodong-Xu/dt-bindings-dma-Add-SpacemiT-K1-PDMA-controller/20250815-132049
> base: 062b3e4a1f880f104a8d4b90b767788786aa7b78
> patch link: https://lore.kernel.org/r/20250815-working_dma_0701_v2-v4-4-62145ab6ea30%40riscstar.com
> patch subject: [PATCH v4 4/8] dmaengine: mmp_pdma: Add operations structure for controller abstraction
> config: parisc-randconfig-r072-20250818 (https://download.01.org/0day-ci/archive/20250818/202508181040.az8RxLrG-lkp@intel.com/config)
> compiler: hppa-linux-gcc (GCC) 8.5.0
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@...el.com>
> | Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
> | Closes: https://lore.kernel.org/r/202508181040.az8RxLrG-lkp@intel.com/
>
> smatch warnings:
> drivers/dma/mmp_pdma.c:546 mmp_pdma_prep_memcpy() warn: variable dereferenced before check 'dchan' (see line 542)
> drivers/dma/mmp_pdma.c:712 mmp_pdma_prep_dma_cyclic() warn: variable dereferenced before check 'dchan' (see line 708)
>
> vim +/dchan +546 drivers/dma/mmp_pdma.c
>
> c8acd6aa6bed3c Zhangfei Gao 2012-09-03 536 static struct dma_async_tx_descriptor *
> c8acd6aa6bed3c Zhangfei Gao 2012-09-03 537 mmp_pdma_prep_memcpy(struct dma_chan *dchan,
> c8acd6aa6bed3c Zhangfei Gao 2012-09-03 538 dma_addr_t dma_dst, dma_addr_t dma_src,
> c8acd6aa6bed3c Zhangfei Gao 2012-09-03 539 size_t len, unsigned long flags)
> c8acd6aa6bed3c Zhangfei Gao 2012-09-03 540 {
> c8acd6aa6bed3c Zhangfei Gao 2012-09-03 541 struct mmp_pdma_chan *chan;
> 918da7ee50b22b Guodong Xu 2025-08-15 @542 struct mmp_pdma_device *pdev = to_mmp_pdma_dev(dchan->device);
> ^^^^^^^^^^^^^
> The patch adds a new dereference
>
> c8acd6aa6bed3c Zhangfei Gao 2012-09-03 543 struct mmp_pdma_desc_sw *first = NULL, *prev = NULL, *new;
> c8acd6aa6bed3c Zhangfei Gao 2012-09-03 544 size_t copy = 0;
> c8acd6aa6bed3c Zhangfei Gao 2012-09-03 545
> c8acd6aa6bed3c Zhangfei Gao 2012-09-03 @546 if (!dchan)
> ^^^^^^
> But the old existing code assumed dchan could be NULL
>
Thank you for the report and findings.
This and the next one, they are bugs, and I will
fix them in the next version.
BR,
Guodong
> c8acd6aa6bed3c Zhangfei Gao 2012-09-03 547 return NULL;
> c8acd6aa6bed3c Zhangfei Gao 2012-09-03 548
> c8acd6aa6bed3c Zhangfei Gao 2012-09-03 549 if (!len)
> c8acd6aa6bed3c Zhangfei Gao 2012-09-03 550 return NULL;
> c8acd6aa6bed3c Zhangfei Gao 2012-09-03 551
> c8acd6aa6bed3c Zhangfei Gao 2012-09-03 552 chan = to_mmp_pdma_chan(dchan);
>
> [ snip ]
>
> 2b7f65b11d87f9 Joe Perches 2013-11-17 701 static struct dma_async_tx_descriptor *
> 2b7f65b11d87f9 Joe Perches 2013-11-17 702 mmp_pdma_prep_dma_cyclic(struct dma_chan *dchan,
> 2b7f65b11d87f9 Joe Perches 2013-11-17 703 dma_addr_t buf_addr, size_t len, size_t period_len,
> 2b7f65b11d87f9 Joe Perches 2013-11-17 704 enum dma_transfer_direction direction,
> 31c1e5a1350ae8 Laurent Pinchart 2014-08-01 705 unsigned long flags)
> 50440d74aae318 Daniel Mack 2013-08-21 706 {
> 50440d74aae318 Daniel Mack 2013-08-21 707 struct mmp_pdma_chan *chan;
> 918da7ee50b22b Guodong Xu 2025-08-15 @708 struct mmp_pdma_device *pdev = to_mmp_pdma_dev(dchan->device);
> ^^^^^^^^^^^^^
>
>
> 50440d74aae318 Daniel Mack 2013-08-21 709 struct mmp_pdma_desc_sw *first = NULL, *prev = NULL, *new;
> 50440d74aae318 Daniel Mack 2013-08-21 710 dma_addr_t dma_src, dma_dst;
> 50440d74aae318 Daniel Mack 2013-08-21 711
> 50440d74aae318 Daniel Mack 2013-08-21 @712 if (!dchan || !len || !period_len)
> ^^^^^^
> Same.
>
>
> 50440d74aae318 Daniel Mack 2013-08-21 713 return NULL;
> 50440d74aae318 Daniel Mack 2013-08-21 714
> 50440d74aae318 Daniel Mack 2013-08-21 715 /* the buffer length must be a multiple of period_len */
>
> --
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki
>
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