Re: [RFC/PATCH] usb/xhci: avoid kernel panic on xhci_suspend()
From: Greg KH
Date: Tue Jan 07 2014 - 20:46:16 EST
On Tue, Jan 07, 2014 at 05:44:26PM -0800, David Cohen wrote:
> From: jianqian <jianqiang.tang@xxxxxxxxx>
> There is a possible kernel panic faced on xhci_suspend().
> Due to kernel modified the hub autosupend_delay to 0s, after usb1 root
> hub finishes initialization, it will trigger runtime_suspend and then
> it will trigger xhci runtime suspend. But at that time, if
> xhci->shared_hcd is still doing initialization, it is possible to face
> null pointer kernel panic in xhci_suspend() function.
> This patch checks if xhci->shared_hcd is null to avoid panic.
> Signed-off-by: jianqian <jianqiang.tang@xxxxxxxxx>
> Signed-off-by: David Cohen <david.a.cohen@xxxxxxxxxxxxxxx>
> This is the kernel panic. The bug was discovered on current LTS kernel 3.10, as
> showed on logs. But the problem does not seem to be fixed so far.
> Maybe we should consider apply it on kernel >= 3.10?
How do you trigger this? I've never seen anyone report this problem
before, is there something different in the hardware you are using that
enables this to be triggered easier?
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