On 06/13/2014 09:39 PM, Alan Stern wrote:
On Fri, 13 Jun 2014, Yang,Wei wrote:
On 06/09/2014 02:19 PM, 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, because the spinlock isn't held
at this point.
Signed-off-by: Yang Wei <Wei.Yang@xxxxxxxxxxxxx>
Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/gadget/f_mass_storage.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
Hi Alan,
Thanks for your review, there are a few changes in v3:
1) Fix a coding style issue.
2) Refine the commit log
Regards
Wei
Ping, Alan, What do you think of it?
You should not have added my "Signed-off-by:"; I did not give you
permission to do that.
Sorry for it, I considered that you give me a few advice and hep me to
refine the commit log,
so I added your signed off. Sorry again!
Michal's comment about common->new_fsg not being protected by the lock
is a good one. It would be better for the patch description to say:
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().
With that change, you may add
Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Okay, I would use the above description in v4.
Regards
Wei
Alan Stern
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