From d25d85061bd856d6be221626605319154f9b5043 Mon Sep 17 00:00:00 2001 From: Wesley Cheng Date: Thu, 29 Jul 2021 00:33:14 -0700 Subject: usb: dwc3: gadget: Use list_replace_init() before traversing lists 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, 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. Example call stack: Thread#1: __dwc3_gadget_ep_set_halt() - CLEAR HALT -> dwc3_gadget_ep_cleanup_cancelled_requests() ->list_for_each_entry_safe() ->dwc3_gadget_giveback(n) ->dwc3_gadget_del_and_unmap_request()- n deleted[cancelled_list] ->spin_unlock ->Thread#2 executes ... ->dwc3_gadget_giveback(n+1) ->Already removed! Thread#2: dwc3_gadget_pullup() ->waiting for dwc3 spin_lock ... ->Thread#1 released lock ->dwc3_stop_active_transfers() ->dwc3_remove_requests() ->fetches n+1 item from cancelled_list (n removed by Thread#1) ->dwc3_gadget_giveback() ->dwc3_gadget_del_and_unmap_request()- n+1 deleted[cancelled_list] ->spin_unlock Fix this condition by utilizing list_replace_init(), and traversing through a local copy of the current elements in the endpoint lists. This will also set the parent list as empty, so if another thread is also looping through the list, it will be empty on the next iteration. Fixes: d4f1afe5e896 ("usb: dwc3: gadget: move requests to cancelled_list") Cc: stable Acked-by: Felipe Balbi Signed-off-by: Wesley Cheng Link: https://lore.kernel.org/r/1627543994-20327-1-git-send-email-wcheng@codeaurora.org Signed-off-by: Greg Kroah-Hartman --- drivers/usb/dwc3/gadget.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) (limited to 'drivers/usb/dwc3/gadget.c') diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index 45f2bc0807e8..a1b262669574 100644 --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -1741,9 +1741,13 @@ static void dwc3_gadget_ep_cleanup_cancelled_requests(struct dwc3_ep *dep) { struct dwc3_request *req; struct dwc3_request *tmp; + struct list_head local; struct dwc3 *dwc = dep->dwc; - list_for_each_entry_safe(req, tmp, &dep->cancelled_list, list) { +restart: + list_replace_init(&dep->cancelled_list, &local); + + list_for_each_entry_safe(req, tmp, &local, list) { dwc3_gadget_ep_skip_trbs(dep, req); switch (req->status) { case DWC3_REQUEST_STATUS_DISCONNECTED: @@ -1761,6 +1765,9 @@ static void dwc3_gadget_ep_cleanup_cancelled_requests(struct dwc3_ep *dep) break; } } + + if (!list_empty(&dep->cancelled_list)) + goto restart; } static int dwc3_gadget_ep_dequeue(struct usb_ep *ep, @@ -2958,8 +2965,12 @@ static void dwc3_gadget_ep_cleanup_completed_requests(struct dwc3_ep *dep, { struct dwc3_request *req; struct dwc3_request *tmp; + struct list_head local; - list_for_each_entry_safe(req, tmp, &dep->started_list, list) { +restart: + list_replace_init(&dep->started_list, &local); + + list_for_each_entry_safe(req, tmp, &local, list) { int ret; ret = dwc3_gadget_ep_cleanup_completed_request(dep, event, @@ -2967,6 +2978,9 @@ static void dwc3_gadget_ep_cleanup_completed_requests(struct dwc3_ep *dep, if (ret) break; } + + if (!list_empty(&dep->started_list)) + goto restart; } static bool dwc3_gadget_ep_should_continue(struct dwc3_ep *dep) -- cgit v1.2.3 From cb10f68ad8150f243964b19391711aaac5e8ff42 Mon Sep 17 00:00:00 2001 From: Wesley Cheng Date: Tue, 3 Aug 2021 23:24:05 -0700 Subject: usb: dwc3: gadget: Avoid runtime resume if disabling pullup If the device is already in the runtime suspended state, any call to the pullup routine will issue a runtime resume on the DWC3 core device. If the USB gadget is disabling the pullup, then avoid having to issue a runtime resume, as DWC3 gadget has already been halted/stopped. This fixes an issue where the following condition occurs: usb_gadget_remove_driver() -->usb_gadget_disconnect() -->dwc3_gadget_pullup(0) -->pm_runtime_get_sync() -> ret = 0 -->pm_runtime_put() [async] -->usb_gadget_udc_stop() -->dwc3_gadget_stop() -->dwc->gadget_driver = NULL ... dwc3_suspend_common() -->dwc3_gadget_suspend() -->DWC3 halt/stop routine skipped, driver_data == NULL This leads to a situation where the DWC3 gadget is not properly stopped, as the runtime resume would have re-enabled EP0 and event interrupts, and since we avoided the DWC3 gadget suspend, these resources were never disabled. Fixes: 77adb8bdf422 ("usb: dwc3: gadget: Allow runtime suspend if UDC unbinded") Cc: stable Acked-by: Felipe Balbi Signed-off-by: Wesley Cheng Link: https://lore.kernel.org/r/1628058245-30692-1-git-send-email-wcheng@codeaurora.org Signed-off-by: Greg Kroah-Hartman --- drivers/usb/dwc3/gadget.c | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'drivers/usb/dwc3/gadget.c') diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index a1b262669574..b8d4b2d327b2 100644 --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -2256,6 +2256,17 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on) } } + /* + * Avoid issuing a runtime resume if the device is already in the + * suspended state during gadget disconnect. DWC3 gadget was already + * halted/stopped during runtime suspend. + */ + if (!is_on) { + pm_runtime_barrier(dwc->dev); + if (pm_runtime_suspended(dwc->dev)) + return 0; + } + /* * Check the return value for successful resume, or error. For a * successful resume, the DWC3 runtime PM resume routine will handle -- cgit v1.2.3