Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752742AbaFMNiY (ORCPT ); Fri, 13 Jun 2014 09:38:24 -0400 Received: from mail-wg0-f73.google.com ([74.125.82.73]:34513 "EHLO mail-wg0-f73.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752083AbaFMNiO (ORCPT ); Fri, 13 Jun 2014 09:38:14 -0400 From: Michal Nazarewicz To: Felipe Balbi Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, Alan Stern , Yang Wei , Michal Nazarewicz Subject: [PATCHv4 6/6] usb: gadget: f_mass_storage: Fix a warning while loading g_mass_storage Date: Fri, 13 Jun 2014 15:38:09 +0200 Message-Id: <1402666689-4971-7-git-send-email-mina86@mina86.com> X-Mailer: git-send-email 2.0.0.526.g5318336 In-Reply-To: <1402666689-4971-1-git-send-email-mina86@mina86.com> References: <1402666689-4971-1-git-send-email-mina86@mina86.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org While loading g_mass_storage module, the following warning can trigger: 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 is that the existing code fails to take into account the possibility that common->new_fsg can change while do_set_interface() is running, because the spinlock does not protect it. Change the code so that the common->new_fsg field is protected by the common->lock spin lock. Reported-by: Yang Wei Signed-off-by: Michal Nazarewicz --- drivers/usb/gadget/f_mass_storage.c | 54 +++++++++++++++++++++++-------------- 1 file changed, 34 insertions(+), 20 deletions(-) diff --git a/drivers/usb/gadget/f_mass_storage.c b/drivers/usb/gadget/f_mass_storage.c index b963939..bd663c2 100644 --- a/drivers/usb/gadget/f_mass_storage.c +++ b/drivers/usb/gadget/f_mass_storage.c @@ -264,7 +264,7 @@ struct fsg_common { /* filesem protects: backing files in use */ struct rw_semaphore filesem; - /* lock protects: state, all the req_busy's */ + /* lock protects: state, all the req_busy's, and new_fsg */ spinlock_t lock; struct usb_ep *ep0; /* Copy of gadget->ep0 */ @@ -407,23 +407,39 @@ static void wakeup_thread(struct fsg_common *common) wake_up_process(common->thread_task); } -static void raise_exception(struct fsg_common *common, enum fsg_state new_state) +static void __raise_exception(struct fsg_common *common, + enum fsg_state new_state) { - unsigned long flags; - /* * Do nothing if a higher-priority exception is already in progress. * If a lower-or-equal priority exception is in progress, preempt it * and notify the main thread by sending it a signal. */ + if (common->state > new_state) + return; + + common->exception_req_tag = common->ep0_req_tag; + common->state = new_state; + if (common->thread_task) + send_sig_info(SIGUSR1, SEND_SIG_FORCED, common->thread_task); +} + +static void raise_exception(struct fsg_common *common, enum fsg_state new_state) +{ + unsigned long flags; spin_lock_irqsave(&common->lock, flags); - if (common->state <= new_state) { - common->exception_req_tag = common->ep0_req_tag; - common->state = new_state; - if (common->thread_task) - send_sig_info(SIGUSR1, SEND_SIG_FORCED, - common->thread_task); - } + __raise_exception(common, new_state); + spin_unlock_irqrestore(&common->lock, flags); +} + +static void raise_config_change_exception(struct fsg_common *common, + struct fsg_dev *new_fsg) +{ + unsigned long flags; + + spin_lock_irqsave(&common->lock, flags); + common->new_fsg = new_fsg; + __raise_exception(common, FSG_STATE_CONFIG_CHANGE); spin_unlock_irqrestore(&common->lock, flags); } @@ -2320,16 +2336,14 @@ reset: static int fsg_set_alt(struct usb_function *f, unsigned intf, unsigned alt) { struct fsg_dev *fsg = fsg_from_func(f); - fsg->common->new_fsg = fsg; - raise_exception(fsg->common, FSG_STATE_CONFIG_CHANGE); + raise_config_change_exception(fsg->common, fsg); return USB_GADGET_DELAYED_STATUS; } static void fsg_disable(struct usb_function *f) { struct fsg_dev *fsg = fsg_from_func(f); - fsg->common->new_fsg = NULL; - raise_exception(fsg->common, FSG_STATE_CONFIG_CHANGE); + raise_config_change_exception(fsg->common, NULL); } @@ -2342,6 +2356,7 @@ 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_fsg; unsigned int exception_req_tag; /* @@ -2405,6 +2420,7 @@ static void handle_exception(struct fsg_common *common) common->next_buffhd_to_drain = &common->buffhds[0]; exception_req_tag = common->exception_req_tag; old_state = common->state; + new_fsg = common->new_fsg; if (old_state == FSG_STATE_ABORT_BULK_OUT) common->state = FSG_STATE_STATUS_PHASE; @@ -2460,8 +2476,8 @@ 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_fsg); + if (new_fsg) usb_composite_setup_continue(common->cdev); break; @@ -3178,8 +3194,7 @@ static void fsg_unbind(struct usb_configuration *c, struct usb_function *f) DBG(fsg, "unbind\n"); if (fsg->common->fsg == fsg) { - fsg->common->new_fsg = NULL; - raise_exception(fsg->common, FSG_STATE_CONFIG_CHANGE); + raise_config_change_exception(fsg->common, NULL); /* FIXME: make interruptible or killable somehow? */ wait_event(common->fsg_wait, common->fsg != fsg); } @@ -3665,4 +3680,3 @@ void fsg_config_from_params(struct fsg_config *cfg, cfg->fsg_num_buffers = fsg_num_buffers; } EXPORT_SYMBOL_GPL(fsg_config_from_params); - -- 2.0.0.526.g5318336 -- 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/