Re: [linux-pm] Fundamental flaw in system suspend, exposed by freezer removal

[David Newall <davidn@davidnewall.com>]

David Brownell wrote:
> On Tuesday 26 February 2008, David Newall wrote:
>   
>> Hardware can be inserted and removed while we're in a suspend state; and
>> there's nothing that we can do about it until we resume.  Is it fair to
>> say, then, that having started suspend, we could reasonably ignore any
>> device insertion and removal, and handle it on resume?
>>     
>
> "Ignore" seems a bit strong; those events may be wakeup triggers,
> which would cause the hardware to make it a very short suspend state.
>
> "Defer handling" is more to the point, be it by hardware or software.
>
>   

Of course, "defer".  The insertion has to be handled eventually.  What
I'm wondering is if we can ignore it, and catch it on the resume.


>> Presumably we need to scan for hardware changes on resume.
>>     
>
> Not on most busses I work with; the hardware issues notifications
> whenever the devices are removable.
>   

There's no notification while we're suspended.  Isn't it necessary to
scan all busses on resume, just to know what's on them?