On Mon, Jul 22, 2024 at 6:31 PM Greg Kroah-Hartman
<gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
> On Mon, Jul 22, 2024 at 03:07:38PM +0000, Łukasz Bartosik wrote:
> > DbC driver does not handle ClearFeature Halt requests correctly
> > which in turn may lead to dropping packets on the receive path.
> >
> > Below is a trace capture where due to incorrect handling of
> > ClearFeature Halt packet gets dropped on the receive path.
> >
> > /sys/kernel/debug/tracing # cat trace
> > 1) kworker/10:3-514 [010] d..1. 2925.601843: xhci_dbc_handle_event:
> > EVENT: TRB 000000019588c0e0 status 'Stall Error' len 0 slot 1 ep 2
> > type 'Transfer Event' flags e:C
> >
> > 2) kworker/10:3-514 [010] d..1. 2925.613285: xhci_dbc_handle_event:
> > EVENT: TRB 000000019588bc80 status 'Stall Error' len 1024 slot 1
> > ep 3 type 'Transfer Event' flags e:C
> >
> > 3) kworker/10:3-514 [010] d..1. 2925.619024: xhci_dbc_handle_transfer:
> > BULK: Buffer 0000000244b49800 length 1024 TD size 0 intr 0 type
> > 'Normal' flags b:i:I:c:s:i:e:C
> >
> > 4) kworker/10:3-514 [010] d..1. 2925.619025: xhci_dbc_giveback_request:
> > bulk-in: req 00000000a70b5ad2 length 0/1024 ==> -6
> >
> > 5) kworker/10:3-514 [010] dNs2. 2925.623820: xhci_dbc_gadget_ep_queue:
> > BULK: Buffer 0000000244b49800 length 1024 TD size 0 intr 0 type
> > 'Normal' flags b:i:I:c:s:i:e:c
> >
> > 6) kworker/10:3-514 [010] dNs1. 2925.623823: xhci_dbc_queue_request:
> > bulk-in: req 00000000a70b5ad2 length 0/1024 ==> -115
> >
> > 7) kworker/10:3-514 [010] d..1. 2925.629865: xhci_dbc_handle_event:
> > EVENT: TRB 000000019588bc80 status 'Short Packet' len 1000 slot 1
> > ep 3 type 'Transfer Event' flags e:C
> >
> > 8) kworker/10:3-514 [010] d..1. 2925.635540: xhci_dbc_handle_event:
> > EVENT: TRB 000000019588bc90 status 'Short Packet' len 763 slot 1
> > ep 3 type 'Transfer Event' flags e:C
> >
> > 9) kworker/10:3-514 [010] d..1. 2925.635540: xhci_dbc_handle_transfer:
> > BULK: Buffer 0000000244b49c00 length 1024 TD size 0 intr 0 type
> > 'Normal' flags b:i:I:c:s:i:e:C
> >
> > 10) kworker/10:3-514 [010] d..1. 2925.635541: xhci_dbc_giveback_request:
> > bulk-in: req 00000000b4ec77d7 length 261/1024 ==> 0
> >
> > 11) kworker/10:3-514 [010] dNs2. 2925.635561: xhci_dbc_gadget_ep_queue:
> > BULK: Buffer 0000000244b49c00 length 1024 TD size 0 intr 0 type
> > 'Normal' flags b:i:I:c:s:i:e:c
> >
> > 12) kworker/10:3-514 [010] dNs1. 2925.635562: xhci_dbc_queue_request:
> > bulk-in: req 00000000b4ec77d7 length 0/1024 ==> -115
> >
> > Lines 1 and 2 are Endpoints OUT and IN responses to receiving ClearFeature
> > Halt requests.
> >
> > Line 7 notifies of reception of 24 bytes packet.
> >
> > Line 8 notifies of reception of 261 bytes packet
> >
> > In Lines [9, 12] 261 bytes packet is being processed.
> >
> > However 24 bytes packet gets dropped. The kernel log includes entry which
> > is an indication of a packet drop:
> > [ 127.651845] xhci_hcd 0000:00:0d.0: no matched request
> >
> > This fix adds correct handling of ClearFeature Halt requests
> > by restarting an endpoint which received the request.
> >
> > Fixes: dfba2174dc42 ("usb: xhci: Add DbC support in xHCI driver")
> > Signed-off-by: Łukasz Bartosik <ukaszb@xxxxxxxxxxxx>
> > ---
> > drivers/usb/host/xhci-dbgcap.c | 29 +++++++++++++++++++----------
> > drivers/usb/host/xhci-dbgtty.c | 5 +++++
> > 2 files changed, 24 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/usb/host/xhci-dbgcap.c b/drivers/usb/host/xhci-dbgcap.c
> > index 872d9cddbcef..b7af3a5ac98a 100644
> > --- a/drivers/usb/host/xhci-dbgcap.c
> > +++ b/drivers/usb/host/xhci-dbgcap.c
> > @@ -173,7 +173,7 @@ static void xhci_dbc_giveback(struct dbc_request *req, int status)
> > spin_lock(&dbc->lock);
> > }
> >
> > -static void xhci_dbc_flush_single_request(struct dbc_request *req)
> > +static void xhci_dbc_flush_single_request(struct dbc_request *req, int status)
>
>
> So now we need to look up what "status" is here for every place this is
> called? That's going to be a pain, as you didn't even document it :(
>
The xhci_dbc_flush_single_request is called only in the function
xhci_dbc_flush_endpoint_requests which follows
xhci_dbc_flush_single_request but I will document it.
Thanks,
Lukasz
> thanks,
>
> greg k-h
