Re: [PATCH] net: can: add missing urb->transfer_dma initialization
From: Yasushi SHOJI <hidden>
Date: 2021-07-25 13:27:54
Also in:
lkml, netdev
Hi Pavel, I've tested this patch on top of v5.14-rc2. All good. Tested-by: Yasushi SHOJI <yashi@spacecubics.com> Some nitpicks. On Sun, Jul 25, 2021 at 7:36 PM Pavel Skripkin [off-list ref] wrote:
Yasushi reported, that his Microchip CAN Analyzer stopped working since
commit 91c02557174b ("can: mcba_usb: fix memory leak in mcba_usb").
The problem was in missing urb->transfer_dma initialization.
In my previous patch to this driver I refactored mcba_usb_start() code to
avoid leaking usb coherent buffers. To achive it, I passed local stackachieve
variable to usb_alloc_coherent() and then saved it to private array to correctly free all coherent buffers on ->close() call. But I forgot to inialize urb->transfer_dma with variable passed to usb_alloc_coherent().
initialize
quoted hunk ↗ jump to hunk
All of this was causing device to not work, since dma addr 0 is not valid and following log can be found on bug report page, which points exactly to problem described above. [ 33.862175] DMAR: [DMA Write] Request device [00:14.0] PASID ffffffff fault addr 0 [fault reason 05] PTE Write access is not set Bug report: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=990850 Reported-by: Yasushi SHOJI <redacted> Fixes: 91c02557174b ("can: mcba_usb: fix memory leak in mcba_usb") Signed-off-by: Pavel Skripkin <redacted> --- drivers/net/can/usb/mcba_usb.c | 2 ++ 1 file changed, 2 insertions(+)diff --git a/drivers/net/can/usb/mcba_usb.c b/drivers/net/can/usb/mcba_usb.c index a45865bd7254..a1a154c08b7f 100644 --- a/drivers/net/can/usb/mcba_usb.c +++ b/drivers/net/can/usb/mcba_usb.c@@ -653,6 +653,8 @@ static int mcba_usb_start(struct mcba_priv *priv) break; } + urb->transfer_dma = buf_dma; + usb_fill_bulk_urb(urb, priv->udev, usb_rcvbulkpipe(priv->udev, MCBA_USB_EP_IN), buf, MCBA_USB_RX_BUFF_SIZE, --2.32.0
Pavel, thanks again for your quick fix. :-)
Best,
--
yashi