Re: [PATCH v1] xhci: dbc: fix handling ClearFeature Halt requests

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

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@chromium.org>
> ---
>  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 :(

thanks,

greg k-h