On 21-05-07 11:42:03, Wesley Cheng wrote:
> The list_for_each_entry_safe() macro saves the current item (n) and
> the item after (n+1), so that n can be safely removed without
> corrupting the list. However, when traversing the list and removing
> items using gadget giveback, the DWC3 lock is briefly released,
I see dwc3_gadget_del_and_unmap_request remove the list, the lock is
still held there. Am I something wrong?
Peter
> allowing other routines to execute. There is a situation where while
> items are being removed from the cancelled_list using
> dwc3_gadget_ep_cleanup_cancelled_requests(), the pullup disable
> routine is running in parallel (due to UDC unbind). As the cleanup
> routine removes n, and the pullup disable removes n+1, once the
> cleanup retakes the DWC3 lock, it references a request who was already
> removed/handled. With list debug enabled, this leads to a panic.
> Ensure all instances of the macro are replaced where gadget giveback
> is used.
>
> Fixes: d4f1afe5e896 ("usb: dwc3: gadget: move requests to cancelled_list")
> Signed-off-by: Wesley Cheng <wcheng@xxxxxxxxxxxxxx>
> ---
> drivers/usb/dwc3/gadget.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index dd80e5c..efa939b 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -1737,10 +1737,10 @@ static void dwc3_gadget_ep_skip_trbs(struct dwc3_ep *dep, struct dwc3_request *r
> static void dwc3_gadget_ep_cleanup_cancelled_requests(struct dwc3_ep *dep)
> {
> struct dwc3_request *req;
> - struct dwc3_request *tmp;
> struct dwc3 *dwc = dep->dwc;
>
> - list_for_each_entry_safe(req, tmp, &dep->cancelled_list, list) {
> + while (!list_empty(&dep->cancelled_list)) {
> + req = next_request(&dep->cancelled_list);
> dwc3_gadget_ep_skip_trbs(dep, req);
> switch (req->status) {
> case DWC3_REQUEST_STATUS_DISCONNECTED:
> @@ -2935,11 +2935,11 @@ static void dwc3_gadget_ep_cleanup_completed_requests(struct dwc3_ep *dep,
> const struct dwc3_event_depevt *event, int status)
> {
> struct dwc3_request *req;
> - struct dwc3_request *tmp;
>
> - list_for_each_entry_safe(req, tmp, &dep->started_list, list) {
> + while (!list_empty(&dep->started_list)) {
> int ret;
>
> + req = next_request(&dep->started_list);
> ret = dwc3_gadget_ep_cleanup_completed_request(dep, event,
> req, status);
> if (ret)
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>
--
Thanks,
Peter Chen
