Re: [RFC/PATCH] usb/xhci: avoid kernel panic on xhci_suspend()

From: Greg KH
Date: Tue Jan 07 2014 - 20:45:33 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.

That sounds like this is a race that should be fixed properly, not just
papered over, right?


greg k-h
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