Re: [syzbot] INFO: task hung in __input_unregister_device (4)

["Fabio M. De Francesco" <fmdefrancesco@gmail.com>]

On martedì 26 luglio 2022 05:53:36 CEST Tetsuo Handa wrote:
> On 2022/07/23 4:15, Fabio M. De Francesco wrote:
> > I had misunderstood easily what you said because I had no context. I 
have 
> > not yet all the necessary context to prepare a "real" patch. As said, 
it 
> > was only a "proof of concept".
> 
> Well, it seems that the cause of this problem is nothing but lack of 
wake_up()
> after clear_bit(). Debug printk() patch shown below says that 
iforce_usb_out()
>  from interrupt context hit "urb->status -71, exiting" when 
iforce_close()
>  from process context was in progress.
> 

Thanks to keep on working on this issue. As said, that _timeout() was not 
good and the wake ups (better, wake_up_all()) were exactly what you needed.   
Now you have all the necessary information to send a real patch :-)

Thanks,

Fabio

> [  491.314788][ T2962] iforce_close(ffff88807e6b8000) start
> [  491.316393][   T14] usb 1-1: USB disconnect, device number 117
> [  491.320453][ T2962] iforce_send_packet(ffff88807e6b8000) start
> [  491.326488][    C0] iforce 1-1:0.0: urb->status -71, exiting
> [  491.327471][   T14] iforce_usb_disconnect(ffff88807e6b8000) start
> [  491.335041][ T2962] iforce_send_packet(ffff88807e6b8000)=0
> [  491.351266][ T2962] wait_event_interruptible(ffff88807e6b8000) end
> [  491.357778][ T2962] iforce_close(ffff88807e6b8000) end
> [  491.366421][   T14] input_unregister_device(ffff88807e6b8000) end
> [  491.372939][   T14] iforce_usb_disconnect(ffff88807e6b8000) end
> 
> On 2022/07/26 12:08, syzbot wrote:
> > Hello,
> > 
> > syzbot has tested the proposed patch and the reproducer did not trigger 
any issue:
> > 
> > Reported-and-tested-by: 
syzbot+deb6abc36aad4008f407@syzkaller.appspotmail.com
> > 
> > Tested on:
> > 
> > commit:         e0dccc3b Linux 5.19-rc8
> > git tree:       upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?
x=15e470de080000
> > kernel config:  https://syzkaller.appspot.com/x/.config?
x=26034e6fe0075dad
> > dashboard link: https://syzkaller.appspot.com/bug?
extid=deb6abc36aad4008f407
> > compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU 
Binutils for Debian) 2.35.2
> > patch:          https://syzkaller.appspot.com/x/patch.diff?
x=14b307f6080000
> > 
> > Note: testing is done by a robot and is best-effort only.
>