On Wed, Nov 27, 2013 at 05:21:57PM -0700, Shuah Khan wrote:
> On 11/27/2013 02:59 PM, Sarah Sharp wrote:
> >On Mon, Nov 25, 2013 at 11:41:47AM -0700, Shuah Khan wrote:
> >>I started seeing the following on my Samsung Series on 3.12.1
> >>
> >>Is this bad? Looks like the following WARN_ON is firing:
> >>
> >>drivers/usb/host/xhci.c:
> >>
> >> if (WARN_ON(!virt_dev)) {
> >> /*
> >> * In plug/unplug torture test with an NEC controller,
> >> * a zero-dereference was observed once due to
> >>virt_dev = 0.
> >> * Print useful debug rather than crash if it is
> >>observed again!
> >> */
> >> xhci_warn(xhci, "Virt dev invalid for slot_id 0x%x!\n",
> >> udev->slot_id);
> >> return -EINVAL;
> >> }
> >
> >As the comment says, the WARN_ON was there so we can track down why this
> >specific NULL pointer dereference bug could have been hit.
> >
> >What are the specific steps to reproduce this? It looks like it's
> >coming from a device resume path. Did you have auto-suspend enabled for
> >your USB devices, or did this warning occur right after an S3 resume?
> >
> >Can you enable CONFIG_USB_DEBUG and CONFIG_DYNAMIC_DEBUG, and send me
> >dmesg starting from just before you trigger the WARN_ON()? I need to
> >see what the xHCI driver state that causes this might be.
> >
> >Sarah Sharp
>
> I forgot to mention that this problem is seen when I run
> suspend-to-disk test in reboot mode. Reproduced it again on
> 3.12.2-rc1 once and dmesg buffer wrapped around before I could save
> the log.
Do you have CONFIG_LOG_BUF_SHIFT set to 21? That might help you capture
dmesg.
> I enabled CONFIG_USB_DEBUG and I already had CONFIG_DYNAMIC_DEBUG
> enabled in config.
>
> It doesn't seem to happen every time I to suspend-to-disk. I will
> try again and send you the log.
Ok, thanks!
Sarah Sharp
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