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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 416C6C25B4E for ; Sun, 22 Jan 2023 15:24:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231350AbjAVPYZ (ORCPT ); Sun, 22 Jan 2023 10:24:25 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52820 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231357AbjAVPYY (ORCPT ); Sun, 22 Jan 2023 10:24:24 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B439F1CAC6 for ; Sun, 22 Jan 2023 07:24:23 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 4DFA060C44 for ; Sun, 22 Jan 2023 15:24:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5BD32C433EF; Sun, 22 Jan 2023 15:24:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1674401062; bh=MlQYjp4QBINGF+h3nPJyzdLvWl6RcXFS8j9Tlxlv3ak=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2bG6uQdRCOKL6fVNuAf2/kcC2Mp4FbS9ejEQiVXm848AF4dnH0RDRu/kzz70nrGuP fLPydfo9Fgoh8xz6z70dkGwob2GrctnAt3W4XpiUcLmgLmhfJSd+tmVLy07Hq4KAP9 2xmWP8Mn0Yn38mVhneacQxOUH1uiKrAtbjojPOpI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Stefan Wahren , Matthias Kaehlcke Subject: [PATCH 6.1 067/193] usb: misc: onboard_hub: Move attach work to the driver Date: Sun, 22 Jan 2023 16:03:16 +0100 Message-Id: <20230122150249.423977392@linuxfoundation.org> X-Mailer: git-send-email 2.39.1 In-Reply-To: <20230122150246.321043584@linuxfoundation.org> References: <20230122150246.321043584@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Matthias Kaehlcke commit cde37881e2e14590675d0acdfbad408300d9ca95 upstream. Currently each onboard_hub platform device owns an 'attach' work, which is scheduled when the device probes. With this deadlocks have been reported on a Raspberry Pi 3 B+ [1], which has nested onboard hubs. The flow of the deadlock is something like this (with the onboard_hub driver built as a module) [2]: - USB root hub is instantiated - core hub driver calls onboard_hub_create_pdevs(), which creates the 'raw' platform device for the 1st level hub - 1st level hub is probed by the core hub driver - core hub driver calls onboard_hub_create_pdevs(), which creates the 'raw' platform device for the 2nd level hub - onboard_hub platform driver is registered - platform device for 1st level hub is probed - schedules 'attach' work - platform device for 2nd level hub is probed - schedules 'attach' work - onboard_hub USB driver is registered - device (and parent) lock of hub is held while the device is re-probed with the onboard_hub driver - 'attach' work (running in another thread) calls driver_attach(), which blocks on one of the hub device locks - onboard_hub_destroy_pdevs() is called by the core hub driver when one of the hubs is detached - destroying the pdevs invokes onboard_hub_remove(), which waits for the 'attach' work to complete - waits forever, since the 'attach' work can't acquire the device lock Use a single work struct for the driver instead of having a work struct per onboard hub platform driver instance. With that it isn't necessary to cancel the work in onboard_hub_remove(), which fixes the deadlock. The work is only cancelled when the driver is unloaded. [1] https://lore.kernel.org/r/d04bcc45-3471-4417-b30b-5cf9880d785d@i2se.com/ [2] https://lore.kernel.org/all/Y6OrGbqaMy2iVDWB@google.com/ Cc: stable@vger.kernel.org Fixes: 8bc063641ceb ("usb: misc: Add onboard_usb_hub driver") Link: https://lore.kernel.org/r/d04bcc45-3471-4417-b30b-5cf9880d785d@i2se.com/ Link: https://lore.kernel.org/all/Y6OrGbqaMy2iVDWB@google.com/ Reported-by: Stefan Wahren Signed-off-by: Matthias Kaehlcke Link: https://lore.kernel.org/r/20230110172954.v2.2.I16b51f32db0c32f8a8532900bfe1c70c8572881a@changeid Signed-off-by: Greg Kroah-Hartman --- drivers/usb/misc/onboard_usb_hub.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) --- a/drivers/usb/misc/onboard_usb_hub.c +++ b/drivers/usb/misc/onboard_usb_hub.c @@ -27,7 +27,10 @@ #include "onboard_usb_hub.h" +static void onboard_hub_attach_usb_driver(struct work_struct *work); + static struct usb_device_driver onboard_hub_usbdev_driver; +static DECLARE_WORK(attach_usb_driver_work, onboard_hub_attach_usb_driver); /************************** Platform driver **************************/ @@ -45,7 +48,6 @@ struct onboard_hub { bool is_powered_on; bool going_away; struct list_head udev_list; - struct work_struct attach_usb_driver_work; struct mutex lock; }; @@ -271,8 +273,7 @@ static int onboard_hub_probe(struct plat * This needs to be done deferred to avoid self-deadlocks on systems * with nested onboard hubs. */ - INIT_WORK(&hub->attach_usb_driver_work, onboard_hub_attach_usb_driver); - schedule_work(&hub->attach_usb_driver_work); + schedule_work(&attach_usb_driver_work); return 0; } @@ -285,9 +286,6 @@ static int onboard_hub_remove(struct pla hub->going_away = true; - if (&hub->attach_usb_driver_work != current_work()) - cancel_work_sync(&hub->attach_usb_driver_work); - mutex_lock(&hub->lock); /* unbind the USB devices to avoid dangling references to this device */ @@ -447,6 +445,8 @@ static void __exit onboard_hub_exit(void { usb_deregister_device_driver(&onboard_hub_usbdev_driver); platform_driver_unregister(&onboard_hub_driver); + + cancel_work_sync(&attach_usb_driver_work); } module_exit(onboard_hub_exit);