Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752116AbaFCJh1 (ORCPT ); Tue, 3 Jun 2014 05:37:27 -0400 Received: from mail.windriver.com ([147.11.1.11]:45940 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750709AbaFCJhZ (ORCPT ); Tue, 3 Jun 2014 05:37:25 -0400 From: To: , CC: , , Subject: [PATCH v1] USB:gadget: Fix a warning while loading g_mass_storage Date: Tue, 3 Jun 2014 17:37:15 +0800 Message-ID: <1401788235-22621-1-git-send-email-Wei.Yang@windriver.com> X-Mailer: git-send-email 1.7.9.5 MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Yang Wei While loading g_mass_storage module, the following warning is triggered. In fact, it is more easy to reproduce it with RT kernel. WARNING: at drivers/usb/gadget/composite.c: usb_composite_setup_continue: Unexpected call Modules linked in: fat vfat minix nls_cp437 nls_iso8859_1 g_mass_storage [<800179cc>] (unwind_backtrace+0x0/0x104) from [<80619608>] (dump_stack+0x20/0x24) [<80619608>] (dump_stack+0x20/0x24) from [<80025100>] (warn_slowpath_common+0x64/0x74) [<80025100>] (warn_slowpath_common+0x64/0x74) from [<800251cc>] (warn_slowpath_fmt+0x40/0x48) [<800251cc>] (warn_slowpath_fmt+0x40/0x48) from [<7f047774>] (usb_composite_setup_continue+0xb4/0xbc [g_mass_storage]) [<7f047774>] (usb_composite_setup_continue+0xb4/0xbc [g_mass_storage]) from [<7f047ad4>] (handle_exception+0x358/0x3e4 [g_mass_storage]) [<7f047ad4>] (handle_exception+0x358/0x3e4 [g_mass_storage]) from [<7f048080>] (fsg_main_thread+0x520/0x157c [g_mass_storage]) [<7f048080>] (fsg_main_thread+0x520/0x157c [g_mass_storage]) from [<8004bc90>] (kthread+0x98/0x9c) [<8004bc90>] (kthread+0x98/0x9c) from [<8000faec>] (kernel_thread_exit+0x0/0x8) The root cause just likes the following scenario. irq thread composite_disconnect() | |->fsg_disable() fsg->common->new_fsg = NULL and then wake fsg_main_thread with seting common->state to FSG_STATE_CONFIG_CHANGE. fsg_main_thread | |->do_set_interface() irq thread set_config() | |->fsg_set_alt() fsg->common->new_fsg = new_fsg and then also wake up fsg_main_thread with setting common->state to FSG_STATE_CONFIG_CHANGE. |-> if(common->new_fsg) usb_composite_setup_continue() In this case, fsg_main_thread would invoke usb_composite_setup_continue twice, so the second call would trigger the above call trace, as we also save common->new_fsg while changing the common->state. Signed-off-by: Yang Wei --- drivers/usb/gadget/f_mass_storage.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) Hi All, This patch is based on git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-next branch, and is validated it with altera cyclone V board. Thanks Wei diff --git a/drivers/usb/gadget/f_mass_storage.c b/drivers/usb/gadget/f_mass_storage.c index b963939..e3b1798 100644 --- a/drivers/usb/gadget/f_mass_storage.c +++ b/drivers/usb/gadget/f_mass_storage.c @@ -2342,6 +2342,7 @@ static void handle_exception(struct fsg_common *common) struct fsg_buffhd *bh; enum fsg_state old_state; struct fsg_lun *curlun; + struct fsg_dev *new; unsigned int exception_req_tag; /* @@ -2421,6 +2422,7 @@ static void handle_exception(struct fsg_common *common) } common->state = FSG_STATE_IDLE; } + new = common->new_fsg; spin_unlock_irq(&common->lock); /* Carry out any extra actions required for the exception */ @@ -2460,8 +2462,8 @@ static void handle_exception(struct fsg_common *common) break; case FSG_STATE_CONFIG_CHANGE: - do_set_interface(common, common->new_fsg); - if (common->new_fsg) + do_set_interface(common, new); + if (new) usb_composite_setup_continue(common->cdev); break; -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/