Hi Andiry, Sarah,
I was compiling xhci and got a warning that event_trb might be used
uninitialized in handle_tx_event(). Looking at the implementation the
logic is quite convoluted but appears that if the following condition is
true:
!event_seg && ep->skip && usb_endpoint_xfer_isoc(...)
we indeed will end up calling process_*_td(..., event_trb, ...).
I think something like the following is needed...
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 3e8211c..85ae5ef 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -1918,22 +1918,26 @@ static int handle_tx_event(struct xhci_hcd *xhci,
}
td = list_entry(ep_ring->td_list.next, struct xhci_td, td_list);
+
/* Is this a TRB in the currently executing TD? */
event_seg = trb_in_td(ep_ring->deq_seg, ep_ring->dequeue,
td->last_trb, event_dma);
- if (event_seg && ep->skip) {
- xhci_dbg(xhci, "Found td. Clear skip flag.\n");
- ep->skip = false;
- }
- if (!event_seg &&
- (!ep->skip || !usb_endpoint_xfer_isoc(&td->urb->ep->desc))) {
+ if (!event_seg) {
+ if (ep->skip &&
+ usb_endpoint_xfer_isoc(&td->urb->ep->desc)) {
+ ret = 0;
+ goto cleanup;
+ }
/* HC is busted, give up! */
- xhci_err(xhci, "ERROR Transfer event TRB DMA ptr not "
- "part of current TD\n");
+ xhci_err(xhci,
+ "ERROR Transfer event TRB DMA ptr not part of current TD\n");
return -ESHUTDOWN;
- }
+ } else {
+ if (ep->skip) {
+ xhci_dbg(xhci, "Found td. Clear skip flag.\n");
+ ep->skip = false;
+ }
- if (event_seg) {
event_trb = &event_seg->trbs[(event_dma -
event_seg->dma) / sizeof(*event_trb)];
/*
Thanks.
--
Dmitry
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