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Subject: Re: Kexec, DMA, and SMP
From: Stephen Hemminger <shemminger@osdl.org>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Kenneth Sumrall <ken@mvista.com>, suparna@in.ibm.com,
       Corey Minyard <cminyard@mvista.com>,
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On Mon, 2003-02-10 at 21:08, Eric W. Biederman wrote:
> Kenneth Sumrall <ken@mvista.com> writes:
> 
> > > Suparna Bhattacharya <suparna@in.ibm.com> writes:
> 
> > > Agreed.  I guess the primary question is can we trust the current
> > > device shutdown + reboot notifier path or do we need to make some
> > > large changes to avoid it.
> > > 
> > So are the functions registered on the reboot notifier path guaranteed
> > to be non-blocking?  In the kexec on panic case, calls that can block
> > would obviously be a bad thing.  If they can block, perhaps we could add
> > a new flag SYS_PANIC or something like that to tell the driver to only
> > do a non-blocking shutdown of the chip.
> 
Some of the network shutdown reboot notifiers can block.
I found this out the hard way when trying to convert notifiers to use RCU
and discovered many warnings.  So many that the effort was abandoned. 

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