From patchwork Thu Apr 14 18:35:21 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wesley Cheng X-Patchwork-Id: 12813877 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 89E30C433F5 for ; Thu, 14 Apr 2022 18:35:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344651AbiDNSiB (ORCPT ); Thu, 14 Apr 2022 14:38:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59862 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245402AbiDNSiA (ORCPT ); Thu, 14 Apr 2022 14:38:00 -0400 Received: from alexa-out.qualcomm.com (alexa-out.qualcomm.com [129.46.98.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B14A5CA6EB; Thu, 14 Apr 2022 11:35:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; i=@quicinc.com; q=dns/txt; s=qcdkim; t=1649961334; x=1681497334; h=from:to:cc:subject:date:message-id:mime-version; bh=h+skRywFctj+zb0/eFTbPUkBZV7lBmQnhujB9KTMfFY=; b=HXHPQE6J/apviPaA8IAfxPvtAQ7q9kl8tsm4BEJAaxkTlqPUk3SX2DBZ nG2BHvXdS+/oHs/yDK/VMuVxhD+t5PLuOEB80eu2eCXt0ArrykDc4OMHP OKFzgcfcEE3+t74pLPYYThiwS54286BP8dZk/FcMSvW+SEC1CwoUBc2JV U=; Received: from ironmsg08-lv.qualcomm.com ([10.47.202.152]) by alexa-out.qualcomm.com with ESMTP; 14 Apr 2022 11:35:33 -0700 X-QCInternal: smtphost Received: from nasanex01c.na.qualcomm.com ([10.47.97.222]) by ironmsg08-lv.qualcomm.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Apr 2022 11:35:33 -0700 Received: from nalasex01b.na.qualcomm.com (10.47.209.197) by nasanex01c.na.qualcomm.com (10.47.97.222) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.22; Thu, 14 Apr 2022 11:35:33 -0700 Received: from hu-wcheng-lv.qualcomm.com (10.49.16.6) by nalasex01b.na.qualcomm.com (10.47.209.197) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.22; Thu, 14 Apr 2022 11:35:32 -0700 From: Wesley Cheng To: , CC: , , , , Wesley Cheng Subject: [PATCH v3] usb: dwc3: gadget: Replace list_for_each_entry_safe() if using giveback Date: Thu, 14 Apr 2022 11:35:21 -0700 Message-ID: <20220414183521.23451-1-quic_wcheng@quicinc.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 X-Originating-IP: [10.49.16.6] X-ClientProxiedBy: nalasex01a.na.qualcomm.com (10.47.209.196) To nalasex01b.na.qualcomm.com (10.47.209.197) Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org 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 Fixes: d4f1afe5e896 ("usb: dwc3: gadget: move requests to cancelled_list") Signed-off-by: Wesley Cheng --- Changes in v3: - Added endpoint disable check while looping Changes in v2: - Updated commit message with context call stack of an example scenario seen on device drivers/usb/dwc3/gadget.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index ce1b130202c5..10271ac9594d 100644 --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -2001,10 +2001,10 @@ 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: @@ -2021,6 +2021,12 @@ static void dwc3_gadget_ep_cleanup_cancelled_requests(struct dwc3_ep *dep) dwc3_gadget_giveback(dep, req, -ECONNRESET); break; } + /* + * The endpoint is disabled, let the dwc3_remove_requests() + * handle the cleanup. + */ + if (!dep->endpoint.desc) + break; } } @@ -3307,15 +3313,21 @@ 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) break; + /* + * The endpoint is disabled, let the dwc3_remove_requests() + * handle the cleanup. + */ + if (!dep->endpoint.desc) + break; } }