A client driver (renesas_usbhs) assumed that
dmaengine_tx_status() could return the residue even if
the transfer was completed. However, this was not correct
usage [1] and this caused to break getting the residue after
the commit 24461d9792c2 ("dmaengine: virt-dma: Fix access after
free in vchan_complete()") actually. So, this is possible to get
wrong received size if the usb controller gets a short packet.
For example, g_zero driver causes "bad OUT byte" errors.
To use the tx_result from the renesas_usbhs driver when
the transfer is completed, set the tx_result parameters.
Notes that the renesas_usbhs driver needs to update for it.
[1]
https://lore.kernel.org/dmaengine/20200616165550.GP2324254@vkoul-mobl/
Reported-by: Hien Dang <hien.dang.eb@xxxxxxxxxxx>
Fixes: 24461d9792c2 ("dmaengine: virt-dma: Fix access after free in vchan_complete()")
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
---
Changes from v1:
- Set tx_result parameters, not change the dmaengine_tx_status behavior.
https://patchwork.kernel.org/patch/11562783/
drivers/dma/sh/usb-dmac.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/dma/sh/usb-dmac.c b/drivers/dma/sh/usb-dmac.c
index b218a01..8f7ceb6 100644
--- a/drivers/dma/sh/usb-dmac.c
+++ b/drivers/dma/sh/usb-dmac.c
@@ -586,6 +586,8 @@ static void usb_dmac_isr_transfer_end(struct usb_dmac_chan *chan)
desc->residue = usb_dmac_get_current_residue(chan, desc,
desc->sg_index - 1);
desc->done_cookie = desc->vd.tx.cookie;
+ desc->vd.tx_result.result = DMA_TRANS_NOERROR;
+ desc->vd.tx_result.residue = desc->residue;
vchan_cookie_complete(&desc->vd);
/* Restart the next transfer if this driver has a next desc */
--
2.7.4
