Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755212AbdGCNiB (ORCPT ); Mon, 3 Jul 2017 09:38:01 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:34598 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755158AbdGCNhu (ORCPT ); Mon, 3 Jul 2017 09:37:50 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Michal Nazarewicz , Baolin Wang , Felipe Balbi , Jerry Zhang Subject: [PATCH 4.4 028/101] usb: gadget: f_fs: Fix possibe deadlock Date: Mon, 3 Jul 2017 15:34:28 +0200 Message-Id: <20170703133339.295726603@linuxfoundation.org> X-Mailer: git-send-email 2.13.2 In-Reply-To: <20170703133334.237346187@linuxfoundation.org> References: <20170703133334.237346187@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6884 Lines: 138 4.4-stable 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 Cc: Jerry Zhang Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/function/f_fs.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) --- a/drivers/usb/gadget/function/f_fs.c +++ b/drivers/usb/gadget/function/f_fs.c @@ -3463,6 +3463,7 @@ static void ffs_closed(struct ffs_data * { struct ffs_dev *ffs_obj; struct f_fs_opts *opts; + struct config_item *ci; ENTER(); ffs_dev_lock(); @@ -3486,8 +3487,11 @@ static void ffs_closed(struct ffs_data * || !atomic_read(&opts->func_inst.group.cg_item.ci_kref.refcount)) goto done; - unregister_gadget_item(ffs_obj->opts-> - func_inst.group.cg_item.ci_parent->ci_parent); + ci = opts->func_inst.group.cg_item.ci_parent->ci_parent; + ffs_dev_unlock(); + + unregister_gadget_item(ci); + return; done: ffs_dev_unlock(); }