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>
---
Changes v2->v1:
- Documented both xhci_dbc_flush_single_request and
xhci_dbc_flush_endpoint_requests functions.
---
drivers/usb/host/xhci-dbgcap.c | 48 +++++++++++++++++++++++++++-------
drivers/usb/host/xhci-dbgtty.c | 5 ++++
2 files changed, 43 insertions(+), 10 deletions(-)
diff --git a/drivers/usb/host/xhci-dbgcap.c b/drivers/usb/host/xhci-dbgcap.c
index 872d9cddbcef..36ec3242e096 100644
--- a/drivers/usb/host/xhci-dbgcap.c
+++ b/drivers/usb/host/xhci-dbgcap.c
@@ -173,7 +173,17 @@ 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)
+/**
+ * xhci_dbc_flush_single_request - flushes single request
+ * @req: request to flush
+ * @status: 0 or -ERESTART - after the request is flushed it will be queued
+ * back to the endpoint
+ *
+ * -ESHUTDOWN - after the request is flushed it won't be queued back
+ * to the endpoint and if it was last endpoint's request the endpoint
+ * will stay shut
+ */
+static void xhci_dbc_flush_single_request(struct dbc_request *req, int status)
{
union xhci_trb *trb = req->trb;
@@ -183,21 +193,36 @@ static void xhci_dbc_flush_single_request(struct dbc_request *req)
trb->generic.field[3] &= cpu_to_le32(TRB_CYCLE);
trb->generic.field[3] |= cpu_to_le32(TRB_TYPE(TRB_TR_NOOP));
- xhci_dbc_giveback(req, -ESHUTDOWN);
+ xhci_dbc_giveback(req, status);
}
-static void xhci_dbc_flush_endpoint_requests(struct dbc_ep *dep)
+/**
+ * xhci_dbc_flush_endpoint_requests - flushes endpoint's requests
+ * @dep: endpoint to flush requests
+ * @restart: true - after being flushed, the requests will be queued back
+ * to the endpoint and its operation will resume
+ *
+ * false - after flushing last endpoint's request the endpoint will
+ * stay shut
+ */
+static void xhci_dbc_flush_endpoint_requests(struct dbc_ep *dep, bool restart)
{
+ struct list_head *list = &dep->list_pending;
struct dbc_request *req, *tmp;
+ int status = -ESHUTDOWN;
- list_for_each_entry_safe(req, tmp, &dep->list_pending, list_pending)
- xhci_dbc_flush_single_request(req);
+ list_for_each_entry_safe(req, tmp, list, list_pending) {
+ if (restart && list_is_last(&req->list_pending, list))
+ status = -ERESTART;
+
+ xhci_dbc_flush_single_request(req, status);
+ }
}
static void xhci_dbc_flush_requests(struct xhci_dbc *dbc)
{
- xhci_dbc_flush_endpoint_requests(&dbc->eps[BULK_OUT]);
- xhci_dbc_flush_endpoint_requests(&dbc->eps[BULK_IN]);
+ xhci_dbc_flush_endpoint_requests(&dbc->eps[BULK_OUT], false);
+ xhci_dbc_flush_endpoint_requests(&dbc->eps[BULK_IN], false);
}
struct dbc_request *
@@ -718,10 +743,13 @@ static void dbc_handle_xfer_event(struct xhci_dbc *dbc, union xhci_trb *event)
case COMP_TRB_ERROR:
case COMP_BABBLE_DETECTED_ERROR:
case COMP_USB_TRANSACTION_ERROR:
- case COMP_STALL_ERROR:
dev_warn(dbc->dev, "tx error %d detected\n", comp_code);
status = -comp_code;
break;
+ case COMP_STALL_ERROR:
+ /* Restart endpoint */
+ xhci_dbc_flush_endpoint_requests(dep, true);
+ return;
default:
dev_err(dbc->dev, "unknown tx error %d\n", comp_code);
status = -comp_code;
@@ -823,12 +851,12 @@ static enum evtreturn xhci_dbc_do_handle_events(struct xhci_dbc *dbc)
if (ctrl & DBC_CTRL_HALT_IN_TR) {
dep = get_in_ep(dbc);
- xhci_dbc_flush_endpoint_requests(dep);
+ xhci_dbc_flush_endpoint_requests(dep, false);
}
if (ctrl & DBC_CTRL_HALT_OUT_TR) {
dep = get_out_ep(dbc);
- xhci_dbc_flush_endpoint_requests(dep);
+ xhci_dbc_flush_endpoint_requests(dep, false);
}
return EVT_DONE;
diff --git a/drivers/usb/host/xhci-dbgtty.c b/drivers/usb/host/xhci-dbgtty.c
index b74e98e94393..bdf80aa2b28c 100644
--- a/drivers/usb/host/xhci-dbgtty.c
+++ b/drivers/usb/host/xhci-dbgtty.c
@@ -121,6 +121,7 @@ static void dbc_write_complete(struct xhci_dbc *dbc, struct dbc_request *req)
list_add(&req->list_pool, &port->write_pool);
switch (req->status) {
case 0:
+ case -ERESTART:
dbc_start_tx(port);
break;
case -ESHUTDOWN:
@@ -318,6 +319,10 @@ static void dbc_rx_push(struct tasklet_struct *t)
case -ESHUTDOWN:
disconnect = true;
break;
+ case -ERESTART:
+ disconnect = false;
+ req->actual = 0;
+ break;
default:
pr_warn("ttyDBC0: unexpected RX status %d\n",
req->status);
--
2.45.2.1089.g2a221341d9-goog
