Re: [PATCH 03/14] dmaengine: dma350: Check vchan_next_desc() return value
From: Robin Murphy <robin.murphy@arm.com>
Date: 2025-08-29 10:02:16
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On 2025-08-23 4:39 pm, Jisheng Zhang wrote:
vchan_next_desc() may return NULL, check its return value.
IIRC it's important that dch->desc gets set to NULL in that case, otherwise things can go wonky after a completion interrupt - i.e. the current code *is* using the return value both ways, just the sneaky thing is that it does actually depend on "vd" being the first member of d350_desc to do it concisely, sorry I didn't document that. Thanks, Robin.
quoted hunk ↗ jump to hunk
Signed-off-by: Jisheng Zhang <jszhang@kernel.org> --- drivers/dma/arm-dma350.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)diff --git a/drivers/dma/arm-dma350.c b/drivers/dma/arm-dma350.c index 24cbadc5f076..96350d15ed85 100644 --- a/drivers/dma/arm-dma350.c +++ b/drivers/dma/arm-dma350.c@@ -399,11 +399,14 @@ static enum dma_status d350_tx_status(struct dma_chan *chan, dma_cookie_t cookie static void d350_start_next(struct d350_chan *dch) { u32 hdr, *reg; + struct virt_dma_desc *vd; - dch->desc = to_d350_desc(vchan_next_desc(&dch->vc)); - if (!dch->desc) + vd = vchan_next_desc(&dch->vc); + if (!vd) return; + dch->desc = to_d350_desc(vd); + list_del(&dch->desc->vd.node); dch->status = DMA_IN_PROGRESS; dch->cookie = dch->desc->vd.tx.cookie;