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Sashiko AI review found 1 potential issue(s) to consider: > > Pre-existing issues: > - [High] Modifying `chan->free_seg_list` without holding `chan->lock` causes linked list corruption. > -- > > --- Patch [4]: [PATCH V3 4/4] dmaengine: xilinx_dma: Extend metadata handling for AXI DMA and MCDMA --- > commit 7c1e9fcfa16f54b84c1fd0328dc790510cde97be > Author: Suraj Gupta > > dmaengine: xilinx_dma: Extend metadata handling for AXI DMA and MCDMA > > This commit extends metadata handling for AXI DMA and MCDMA to expose > status and sideband information. The metadata pointer now starts at the > descriptor status word instead of the APP fields, and probe logic is > updated to attach metadata_ops when an AXI Stream interface is present. > >> diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c >> index 9b8b6f1acd4ea..03c45369086b8 100644 >> --- a/drivers/dma/xilinx/xilinx_dma.c >> +++ b/drivers/dma/xilinx/xilinx_dma.c > [ ... ] > >> @@ -2623,6 +2653,9 @@ xilinx_mcdma_prep_slave_sg(struct dma_chan *dchan, struct scatterlist *sgl, >> segment->hw.control |= XILINX_MCDMA_BD_EOP; >> } >> >> + if (chan->xdev->has_axistream_connected) >> + desc->async_tx.metadata_ops = &xilinx_dma_metadata_ops; >> + >> return &desc->async_tx; >> >> error: >> xilinx_dma_free_tx_descriptor(chan, desc); > [Severity: High] > This isn't a bug introduced by this patch, but does this error path corrupt > the channel's free segment list? > > When xilinx_mcdma_prep_slave_sg() encounters an error, it calls > xilinx_dma_free_tx_descriptor() without holding chan->lock. This eventually > cascades to xilinx_mcdma_free_tx_segment() and xilinx_dma_free_tx_segment(), > which add the segment back to chan->free_seg_list: > > xilinx_mcdma_free_tx_segment() > list_add_tail(&segment->node, &chan->free_seg_list); > > If another CPU core concurrently calls xilinx_aximcdma_alloc_tx_segment(), > which acquires chan->lock to remove items from this same list, could this > unprotected modification lead to linked list corruption? > > This unprotected error path also appears to be present in > xilinx_dma_tx_submit() when chan->cyclic is true. The locking issue with free_seg_list modification is a valid pre-existing concern, not introduced by this patch.   I'll address this in a separate patch series along with the other pre-existing issues identified in this review.   Thanks,   Neeli Srinivas