From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.codeaurora.org by pdx-caf-mail.web.codeaurora.org (Dovecot) with LMTP id xePmAqFWGVvZZAAAmS7hNA ; Thu, 07 Jun 2018 16:00:48 +0000 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 62B0B607E7; Thu, 7 Jun 2018 16:00:48 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on pdx-caf-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI autolearn=unavailable autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by smtp.codeaurora.org (Postfix) with ESMTP id 9F215601D2; Thu, 7 Jun 2018 16:00:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 9F215601D2 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=decadent.org.uk Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935701AbeFGQAp (ORCPT + 25 others); Thu, 7 Jun 2018 12:00:45 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:39289 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933026AbeFGOJF (ORCPT ); Thu, 7 Jun 2018 10:09:05 -0400 Received: from [148.252.241.226] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.84_2) (envelope-from ) id 1fQvb4-0005Zv-ID; Thu, 07 Jun 2018 15:09:02 +0100 Received: from ben by deadeye with local (Exim 4.91) (envelope-from ) id 1fQvb1-0002pR-Ek; Thu, 07 Jun 2018 15:08:59 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Felipe Balbi" , "Baolin Wang" , "Michal Nazarewicz" Date: Thu, 07 Jun 2018 15:05:21 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 102/410] usb: gadget: f_fs: Fix possibe deadlock In-Reply-To: X-SA-Exim-Connect-IP: 148.252.241.226 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.57-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Baolin Wang commit b3ce3ce02d146841af012d08506b4071db8ffde3 upstream. When system try to close /dev/usb-ffs/adb/ep0 on one core, at the same time another core try to attach new UDC, which will cause deadlock as below scenario. Thus we should release ffs lock before issuing unregister_gadget_item(). [ 52.642225] c1 ====================================================== [ 52.642228] c1 [ INFO: possible circular locking dependency detected ] [ 52.642236] c1 4.4.6+ #1 Tainted: G W O [ 52.642241] c1 ------------------------------------------------------- [ 52.642245] c1 usb ffs open/2808 is trying to acquire lock: [ 52.642270] c0 (udc_lock){+.+.+.}, at: [] usb_gadget_unregister_driver+0x3c/0xc8 [ 52.642272] c1 but task is already holding lock: [ 52.642283] c0 (ffs_lock){+.+.+.}, at: [] ffs_data_clear+0x30/0x140 [ 52.642285] c1 which lock already depends on the new lock. [ 52.642287] c1 the existing dependency chain (in reverse order) is: [ 52.642295] c0 -> #1 (ffs_lock){+.+.+.}: [ 52.642307] c0 [] __lock_acquire+0x20f0/0x2238 [ 52.642314] c0 [] lock_acquire+0xe4/0x298 [ 52.642322] c0 [] mutex_lock_nested+0x7c/0x3cc [ 52.642328] c0 [] ffs_func_bind+0x504/0x6e8 [ 52.642334] c0 [] usb_add_function+0x84/0x184 [ 52.642340] c0 [] configfs_composite_bind+0x264/0x39c [ 52.642346] c0 [] udc_bind_to_driver+0x58/0x11c [ 52.642352] c0 [] usb_udc_attach_driver+0x90/0xc8 [ 52.642358] c0 [] gadget_dev_desc_UDC_store+0xd4/0x128 [ 52.642369] c0 [] configfs_write_file+0xd0/0x13c [ 52.642376] c0 [] vfs_write+0xb8/0x214 [ 52.642381] c0 [] SyS_write+0x54/0xb0 [ 52.642388] c0 [] el0_svc_naked+0x24/0x28 [ 52.642395] c0 -> #0 (udc_lock){+.+.+.}: [ 52.642401] c0 [] print_circular_bug+0x84/0x2e4 [ 52.642407] c0 [] __lock_acquire+0x2138/0x2238 [ 52.642412] c0 [] lock_acquire+0xe4/0x298 [ 52.642420] c0 [] mutex_lock_nested+0x7c/0x3cc [ 52.642427] c0 [] usb_gadget_unregister_driver+0x3c/0xc8 [ 52.642432] c0 [] unregister_gadget_item+0x28/0x44 [ 52.642439] c0 [] ffs_data_clear+0x138/0x140 [ 52.642444] c0 [] ffs_data_reset+0x20/0x6c [ 52.642450] c0 [] ffs_data_closed+0xac/0x12c [ 52.642454] c0 [] ffs_ep0_release+0x20/0x2c [ 52.642460] c0 [] __fput+0xb0/0x1f4 [ 52.642466] c0 [] ____fput+0x20/0x2c [ 52.642473] c0 [] task_work_run+0xb4/0xe8 [ 52.642482] c0 [] do_exit+0x360/0xb9c [ 52.642487] c0 [] do_group_exit+0x4c/0xb0 [ 52.642494] c0 [] get_signal+0x380/0x89c [ 52.642501] c0 [] do_signal+0x154/0x518 [ 52.642507] c0 [] do_notify_resume+0x70/0x78 [ 52.642512] c0 [] work_pending+0x1c/0x20 [ 52.642514] c1 other info that might help us debug this: [ 52.642517] c1 Possible unsafe locking scenario: [ 52.642518] c1 CPU0 CPU1 [ 52.642520] c1 ---- ---- [ 52.642525] c0 lock(ffs_lock); [ 52.642529] c0 lock(udc_lock); [ 52.642533] c0 lock(ffs_lock); [ 52.642537] c0 lock(udc_lock); [ 52.642539] c1 *** DEADLOCK *** [ 52.642543] c1 1 lock held by usb ffs open/2808: [ 52.642555] c0 #0: (ffs_lock){+.+.+.}, at: [] ffs_data_clear+0x30/0x140 [ 52.642557] c1 stack backtrace: [ 52.642563] c1 CPU: 1 PID: 2808 Comm: usb ffs open Tainted: G [ 52.642565] c1 Hardware name: Spreadtrum SP9860g Board (DT) [ 52.642568] c1 Call trace: [ 52.642573] c1 [] dump_backtrace+0x0/0x170 [ 52.642577] c1 [] show_stack+0x20/0x28 [ 52.642583] c1 [] dump_stack+0xa8/0xe0 [ 52.642587] c1 [] print_circular_bug+0x1fc/0x2e4 [ 52.642591] c1 [] __lock_acquire+0x2138/0x2238 [ 52.642595] c1 [] lock_acquire+0xe4/0x298 [ 52.642599] c1 [] mutex_lock_nested+0x7c/0x3cc [ 52.642604] c1 [] usb_gadget_unregister_driver+0x3c/0xc8 [ 52.642608] c1 [] unregister_gadget_item+0x28/0x44 [ 52.642613] c1 [] ffs_data_clear+0x138/0x140 [ 52.642618] c1 [] ffs_data_reset+0x20/0x6c [ 52.642621] c1 [] ffs_data_closed+0xac/0x12c [ 52.642625] c1 [] ffs_ep0_release+0x20/0x2c [ 52.642629] c1 [] __fput+0xb0/0x1f4 [ 52.642633] c1 [] ____fput+0x20/0x2c [ 52.642636] c1 [] task_work_run+0xb4/0xe8 [ 52.642640] c1 [] do_exit+0x360/0xb9c [ 52.642644] c1 [] do_group_exit+0x4c/0xb0 [ 52.642647] c1 [] get_signal+0x380/0x89c [ 52.642651] c1 [] do_signal+0x154/0x518 [ 52.642656] c1 [] do_notify_resume+0x70/0x78 [ 52.642659] c1 [] work_pending+0x1c/0x20 Acked-by: Michal Nazarewicz Signed-off-by: Baolin Wang Signed-off-by: Felipe Balbi [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- drivers/usb/gadget/f_fs.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) --- a/drivers/usb/gadget/f_fs.c +++ b/drivers/usb/gadget/f_fs.c @@ -2998,6 +2998,7 @@ done: static void ffs_closed(struct ffs_data *ffs) { struct ffs_dev *ffs_obj; + struct config_item *ci; ENTER(); ffs_dev_lock(); @@ -3015,8 +3016,11 @@ static void ffs_closed(struct ffs_data * || !ffs_obj->opts->func_inst.group.cg_item.ci_parent) goto done; - unregister_gadget_item(ffs_obj->opts-> - func_inst.group.cg_item.ci_parent->ci_parent); + ci = ffs_obj->opts->func_inst.group.cg_item.ci_parent->ci_parent; + ffs_dev_unlock(); + + unregister_gadget_item(ci); + return; done: ffs_dev_unlock(); }