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This causes a type confusion bug which treats the > head, which is a ls1x_dma_desc, as a ls1x_dma_lli object. Additionally it > goes forwards and prints garbage via the dev_dbg. > > Fix the type confusion bug by only allowing matched LLI descriptor chains > to print the current LLI and residue calculation, as failing to match > should be treated as an unexpected condition. > > Found by the following Coccinelle check: > > scripts/coccinelle/iterators/use_after_iter.cocci > > drivers/dma/loongson/loongson1-apb-dma.c:461:6-9: ERROR: invalid > reference to the index variable of the iterator on line 450 > > Compile test only; Hardware testing by Keguang Zhang. > > Signed-off-by: Mahad Ibrahim > Reviewed-by: Keguang Zhang > Tested-by: Keguang Zhang # on LS1B & LS1C > --- Reviewed-by: Frank Li > > v2: > - encapsulate residue calculation and dev_dbg inside the > list_for_each_entry() macro. Treat non-matching LLI as an unexpected > case. > - link: https://lore.kernel.org/all/20260729143247.6111-1-mahad.ibrahim.dev@gmail.com/ > > > v3: > - Collect tags from Keguang Zhang. > - Repost patch in a new thread. > - Change chan2dev to the newer dmaengine_chan_dev. > > > drivers/dma/loongson/loongson1-apb-dma.c | 27 ++++++++++++++---------- > 1 file changed, 16 insertions(+), 11 deletions(-) > > diff --git a/drivers/dma/loongson/loongson1-apb-dma.c b/drivers/dma/loongson/loongson1-apb-dma.c > index 46b4bfef45e2..e62ab26c8327 100644 > --- a/drivers/dma/loongson/loongson1-apb-dma.c > +++ b/drivers/dma/loongson/loongson1-apb-dma.c > @@ -441,22 +441,27 @@ static enum dma_status ls1x_dma_tx_status(struct dma_chan *dchan, > > /* locate the current lli */ > next_phys = chan->curr_lli->hw[LS1X_DMADESC_NEXT]; > - list_for_each_entry(lli, &desc->lli_list, node) > - if (lli->hw[LS1X_DMADESC_NEXT] == next_phys) > - break; > + list_for_each_entry(lli, &desc->lli_list, node) { > + if (lli->hw[LS1X_DMADESC_NEXT] != next_phys) > + continue; > > - dev_dbg(dmaengine_chan_dev(dchan), "current lli_phys=%pad", > - &lli->phys); > + dev_dbg(dmaengine_chan_dev(dchan), "current lli_phys=%pad\n", > + &lli->phys); > > - /* count the residues */ > - list_for_each_entry_from(lli, &desc->lli_list, node) > - bytes += lli->hw[LS1X_DMADESC_LENGTH] * > - chan->bus_width; > + /* count the residues */ > + list_for_each_entry_from(lli, &desc->lli_list, node) > + bytes += lli->hw[LS1X_DMADESC_LENGTH] * > + chan->bus_width; > + > + dma_set_residue(state, bytes); > + return status; > + } > + > + dev_warn(dmaengine_chan_dev(dchan), > + "unable to locate current lli.\n"); > } > } > > - dma_set_residue(state, bytes); > - > return status; > } > > -- > 2.54.0 >