From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 45CCCC4320A for ; Thu, 29 Jul 2021 07:33:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2741961057 for ; Thu, 29 Jul 2021 07:33:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234627AbhG2HdY (ORCPT ); Thu, 29 Jul 2021 03:33:24 -0400 Received: from so254-9.mailgun.net ([198.61.254.9]:57715 "EHLO so254-9.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234524AbhG2HdW (ORCPT ); Thu, 29 Jul 2021 03:33:22 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1627544000; h=Message-Id: Date: Subject: Cc: To: From: Sender; bh=4dgDA5U7bl0B0ZrmuX/lx0/KoPyld4ncHKTgBOfdJns=; b=Hl4w+fWyh1SWdKAwwqmF2v/LrMVLSzOu55pSZorEzVgfbm+oTZVuev+/C7rlSaXtyAwdb229 MXsq7r4BpCI/FSPBGZdq0WCXqCRTGUkbsTYak9M+YM7uCQy1gmpUD2b+1dHiDgJAUVJe/esQ OFq6/2yugewZnMSgmZ2gNR/0mh8= X-Mailgun-Sending-Ip: 198.61.254.9 X-Mailgun-Sid: WyI0MWYwYSIsICJsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n06.prod.us-east-1.postgun.com with SMTP id 610259be290ea35ee6de35de (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Thu, 29 Jul 2021 07:33:18 GMT Sender: wcheng=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 01AF7C433F1; Thu, 29 Jul 2021 07:33:17 +0000 (UTC) Received: from wcheng-linux.qualcomm.com (i-global254.qualcomm.com [199.106.103.254]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: wcheng) by smtp.codeaurora.org (Postfix) with ESMTPSA id 968BFC4338A; Thu, 29 Jul 2021 07:33:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 968BFC4338A Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=fail smtp.mailfrom=wcheng@codeaurora.org From: Wesley Cheng To: balbi@kernel.org, gregkh@linuxfoundation.org Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, jackp@codeaurora.org, Wesley Cheng Subject: [PATCH] usb: dwc3: gadget: Use list_replace_init() before traversing lists Date: Thu, 29 Jul 2021 00:33:14 -0700 Message-Id: <1627543994-20327-1-git-send-email-wcheng@codeaurora.org> X-Mailer: git-send-email 2.7.4 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 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") Signed-off-by: Wesley Cheng --- Previous patchset: https://lore.kernel.org/linux-usb/1620716636-12422-1-git-send-email-wcheng@codeaurora.org/ --- drivers/usb/dwc3/gadget.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index a29a4ca..3ce6ed9 100644 --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -1926,9 +1926,13 @@ 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: @@ -1946,6 +1950,9 @@ 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, @@ -3190,8 +3197,12 @@ 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, @@ -3199,6 +3210,9 @@ 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) -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project