[PATCH v2 1/8] usb: xhci: Guard all calls to xhci_wait_for_event

[Hector Martin]

xhci_wait_for_event returns NULL on timeout, so the caller always has to
check for that. This addresses immediate explosions in this part
of the code when timeouts happen, but not the root cause for the
timeout.

Signed-off-by: Hector Martin <marcan at marcan.st>
---
 drivers/usb/host/xhci-ring.c | 15 +++++++++++++++
 drivers/usb/host/xhci.c      |  9 +++++++++
 2 files changed, 24 insertions(+)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index c8260cbdf94b..d0960812a47b 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -511,6 +511,9 @@ static void reset_ep(struct usb_device *udev, int ep_index)
 	printf("Resetting EP %d...\n", ep_index);
 	xhci_queue_command(ctrl, 0, udev->slot_id, ep_index, TRB_RESET_EP);
 	event = xhci_wait_for_event(ctrl, TRB_COMPLETION);
+	if (!event)
+		return;
+
 	field = le32_to_cpu(event->trans_event.flags);
 	BUG_ON(TRB_TO_SLOT_ID(field) != udev->slot_id);
 	xhci_acknowledge_event(ctrl);
@@ -519,6 +522,9 @@ static void reset_ep(struct usb_device *udev, int ep_index)
 		(void *)((uintptr_t)ring->enqueue | ring->cycle_state));
 	xhci_queue_command(ctrl, addr, udev->slot_id, ep_index, TRB_SET_DEQ);
 	event = xhci_wait_for_event(ctrl, TRB_COMPLETION);
+	if (!event)
+		return;
+
 	BUG_ON(TRB_TO_SLOT_ID(le32_to_cpu(event->event_cmd.flags))
 		!= udev->slot_id || GET_COMP_CODE(le32_to_cpu(
 		event->event_cmd.status)) != COMP_SUCCESS);
@@ -544,6 +550,9 @@ static void abort_td(struct usb_device *udev, int ep_index)
 	xhci_queue_command(ctrl, 0, udev->slot_id, ep_index, TRB_STOP_RING);
 
 	event = xhci_wait_for_event(ctrl, TRB_TRANSFER);
+	if (!event)
+		return;
+
 	field = le32_to_cpu(event->trans_event.flags);
 	BUG_ON(TRB_TO_SLOT_ID(field) != udev->slot_id);
 	BUG_ON(TRB_TO_EP_INDEX(field) != ep_index);
@@ -552,6 +561,9 @@ static void abort_td(struct usb_device *udev, int ep_index)
 	xhci_acknowledge_event(ctrl);
 
 	event = xhci_wait_for_event(ctrl, TRB_COMPLETION);
+	if (!event)
+		return;
+
 	BUG_ON(TRB_TO_SLOT_ID(le32_to_cpu(event->event_cmd.flags))
 		!= udev->slot_id || GET_COMP_CODE(le32_to_cpu(
 		event->event_cmd.status)) != COMP_SUCCESS);
@@ -561,6 +573,9 @@ static void abort_td(struct usb_device *udev, int ep_index)
 		(void *)((uintptr_t)ring->enqueue | ring->cycle_state));
 	xhci_queue_command(ctrl, addr, udev->slot_id, ep_index, TRB_SET_DEQ);
 	event = xhci_wait_for_event(ctrl, TRB_COMPLETION);
+	if (!event)
+		return;
+
 	BUG_ON(TRB_TO_SLOT_ID(le32_to_cpu(event->event_cmd.flags))
 		!= udev->slot_id || GET_COMP_CODE(le32_to_cpu(
 		event->event_cmd.status)) != COMP_SUCCESS);
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 5cacf0769ec7..d13cbff9b372 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -451,6 +451,9 @@ static int xhci_configure_endpoints(struct usb_device *udev, bool ctx_change)
 	xhci_queue_command(ctrl, in_ctx->dma, udev->slot_id, 0,
 			   ctx_change ? TRB_EVAL_CONTEXT : TRB_CONFIG_EP);
 	event = xhci_wait_for_event(ctrl, TRB_COMPLETION);
+	if (!event)
+		return -ETIMEDOUT;
+
 	BUG_ON(TRB_TO_SLOT_ID(le32_to_cpu(event->event_cmd.flags))
 		!= udev->slot_id);
 
@@ -647,6 +650,9 @@ static int xhci_address_device(struct usb_device *udev, int root_portnr)
 	xhci_queue_command(ctrl, virt_dev->in_ctx->dma,
 			   slot_id, 0, TRB_ADDR_DEV);
 	event = xhci_wait_for_event(ctrl, TRB_COMPLETION);
+	if (!event)
+		return -ETIMEDOUT;
+
 	BUG_ON(TRB_TO_SLOT_ID(le32_to_cpu(event->event_cmd.flags)) != slot_id);
 
 	switch (GET_COMP_CODE(le32_to_cpu(event->event_cmd.status))) {
@@ -722,6 +728,9 @@ static int _xhci_alloc_device(struct usb_device *udev)
 
 	xhci_queue_command(ctrl, 0, 0, 0, TRB_ENABLE_SLOT);
 	event = xhci_wait_for_event(ctrl, TRB_COMPLETION);
+	if (!event)
+		return -ETIMEDOUT;
+
 	BUG_ON(GET_COMP_CODE(le32_to_cpu(event->event_cmd.status))
 		!= COMP_SUCCESS);
 

-- 
2.41.0