Re: Kexec, DMA, and SMP

Stephen Hemminger
2003-02-11T16:59:37Z

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.