Re: USBDEVFS_RESET deadlocks USB bus.

[Zephaniah E. Hull]

On Fri, Jun 04, 2004 at 12:52:47PM -0700, Greg KH wrote:
> On Fri, Jun 04, 2004 at 03:39:11PM -0400, Zephaniah E. Hull wrote:
> > Starting at 2.6.7-rc1 or so (that is when we first noticed it) the new
> > pilot-link libusb back end started deadlocking the entire USB bus that
> > the palm device was on.
> > 
> > I have finally tracked it down to happening when we make the
> > USBDEVFS_RESET ioctl, we never return from it and from that point on the
> > bus in question is completely dead, no processing is done, no
> > notifications of devices being plugged in or unplugged.
> > 
> > This is still happening in 2.6.7-rc2-mm1.
> > 
> > It seems to happen with both the UHCI and OHCI back ends, so it is
> > probably above that.
> > 
> > Given that there were heavy locking changes, I suspect that the case in
> > question got screwed up somehow.
> 
> This needs to go to the linux-usb-devel list, now CC:

Whoops.
> 
> Anyway, can you look at the output of SysRq-T and see where the
> processes are hung?

lt-pilot-xfer D 00000000     0 11415   2709                     (NOTLB)
d2ad3eb0 00000086 c022391a 00000000 3231203a 000a2e35 00000001 d2ad3ea7
       d4edd000 d7fc8a00 c8449790 00000000 abb31900 000f447a c4bae4b8 c977d824
       00000246 d2ad2000 d2ad3eec c0336735 c977d82c c4bae310 00000001 c4bae310
Call Trace:
 [<c0336735>] __down+0x85/0x120
 [<c033692f>] __down_failed+0xb/0x14
 [<c026af27>] .text.lock.hub+0x69/0x82
 [<c0272b7f>] usbdev_ioctl+0x19f/0x710
 [<c015a45d>] file_ioctl+0x5d/0x170
 [<c015a686>] sys_ioctl+0x116/0x250
 [<c0103f8f>] syscall_call+0x7/0xb

This is on 2.6.7-rc2-mm1.

Please keep me in the reply list if we are pulled off of linux-kernel,
as I am not currently on linux-usb-devel.

-- 
	1024D/E65A7801 Zephaniah E. Hull <warp@xxxxxxxxxxxxxxxx>
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<cas> well there ya go.  say something stupid in irc and have it
      immortalised forever in someone's .sig file

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