Messages in this thread Patch in this message | | | From | <> | Subject | [PATCH v1] USB:gadget: Fix a warning while loading g_mass_storage | Date | Tue, 3 Jun 2014 17:37:15 +0800 |
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From: Yang Wei <Wei.Yang@windriver.com>
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 <Wei.Yang@windriver.com> --- 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
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