| Message ID | 1711536564-12919-1-git-send-email-jpinto@synopsys.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 333e11bf47fa8d477db90e2900b1ed3c9ae9b697 |
| Headers | show |
| Series | [RESEND] Avoid hw_desc array overrun in dw-axi-dmac | expand |
On Wed, 27 Mar 2024 10:49:24 +0000, Joao Pinto wrote: > I have a use case where nr_buffers = 3 and in which each descriptor is composed by 3 > segments, resulting in the DMA channel descs_allocated to be 9. Since axi_desc_put() > handles the hw_desc considering the descs_allocated, this scenario would result in a > kernel panic (hw_desc array will be overrun). > > To fix this, the proposal is to add a new member to the axi_dma_desc structure, > where we keep the number of allocated hw_descs (axi_desc_alloc()) and use it in > axi_desc_put() to handle the hw_desc array correctly. > > [...] Applied, thanks! [1/1] Avoid hw_desc array overrun in dw-axi-dmac commit: 333e11bf47fa8d477db90e2900b1ed3c9ae9b697 Best regards,
diff --git a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c index a86a81f..b39f37a 100644 --- a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c +++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c @@ -302,6 +302,7 @@ static struct axi_dma_desc *axi_desc_alloc(u32 num) kfree(desc); return NULL; } + desc->nr_hw_descs = num; return desc; } @@ -328,7 +329,7 @@ static struct axi_dma_lli *axi_desc_get(struct axi_dma_chan *chan, static void axi_desc_put(struct axi_dma_desc *desc) { struct axi_dma_chan *chan = desc->chan; - int count = atomic_read(&chan->descs_allocated); + int count = desc->nr_hw_descs; struct axi_dma_hw_desc *hw_desc; int descs_put; @@ -1139,9 +1139,6 @@ static void axi_chan_block_xfer_complete(struct axi_dma_chan *chan) /* Remove the completed descriptor from issued list before completing */ list_del(&vd->node); vchan_cookie_complete(vd); - - /* Submit queued descriptors after processing the completed ones */ - axi_chan_start_first_queued(chan); } out: diff --git a/drivers/dma/dw-axi-dmac/dw-axi-dmac.h b/drivers/dma/dw-axi-dmac/dw-axi-dmac.h index 454904d..ac571b4 100644 --- a/drivers/dma/dw-axi-dmac/dw-axi-dmac.h +++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac.h @@ -104,6 +104,7 @@ struct axi_dma_desc { u32 completed_blocks; u32 length; u32 period_len; + u32 nr_hw_descs; }; struct axi_dma_chan_config {
I have a use case where nr_buffers = 3 and in which each descriptor is composed by 3 segments, resulting in the DMA channel descs_allocated to be 9. Since axi_desc_put() handles the hw_desc considering the descs_allocated, this scenario would result in a kernel panic (hw_desc array will be overrun). To fix this, the proposal is to add a new member to the axi_dma_desc structure, where we keep the number of allocated hw_descs (axi_desc_alloc()) and use it in axi_desc_put() to handle the hw_desc array correctly. Additionally I propose to remove the axi_chan_start_first_queued() call after completing the transfer, since it was identified that unbalance can occur (started descriptors can be interrupted and transfer ignored due to DMA channel not being enabled). Signed-off-by: Joao Pinto <jpinto@synopsys.com> --- drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c | 7 ++----- drivers/dma/dw-axi-dmac/dw-axi-dmac.h | 1 + 2 files changed, 3 insertions(+), 5 deletions(-)