Re: [PATCH] USB:gadget: Fix a warning while loading g_mass_storage

[Yang,Wei]

On 06/15/2014 10:42 AM, Yang,Wei wrote:
> Its v4, sorry for missing it in subject.

Alan, How about this version?

Cheers
Wei
> Regards
> Wei
> On 06/15/2014 10:40 AM, Wei.Yang@xxxxxxxxxxxxx wrote:
> > From: Yang Wei <Wei.Yang@xxxxxxxxxxxxx>
> >
> > While loading g_mass_storage module, the following warning
> > is triggered.
> >
> > 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, so the value of common->new_fsg
> > that gets tested after do_set_interface returns needs to be
> > the same as the value used by do_set_interface.
> >
> > Signed-off-by: Yang Wei <Wei.Yang@xxxxxxxxxxxxx>
> > Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> > ---
> >   drivers/usb/gadget/f_mass_storage.c |    6 ++++--
> >   1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > Changes in v3 ----> v4
> >
> > move "new_fsg = common->new_fsg" out of comm->lock protection, and 
> > refine the commit log.
> >
> > Thanks
> > Wei
> >
> > diff --git a/drivers/usb/gadget/f_mass_storage.c 
> > b/drivers/usb/gadget/f_mass_storage.c
> > index b963939..a7e24c8 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_fsg;
> >       unsigned int        exception_req_tag;
> >         /*
> > @@ -2460,8 +2461,9 @@ 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)
> > +        new_fsg = common->new_fsg;
> > +        do_set_interface(common, new_fsg);
> > +        if (new_fsg)
> >               usb_composite_setup_continue(common->cdev);
> >           break;

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