linux-kernel - Re: [PATCH] pci_get_device call from interrupt in reboot fixups

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Date:	Tue, 7 Aug 2007 00:42:32 -0700
From:	Greg KH <gregkh@...e.de>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	"Denis V. Lunev" <den@...ru>, "Denis V. Lunev" <den@...nvz.org>,
	dev@...nvz.org, devel@...nvz.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] pci_get_device call from interrupt in reboot fixups

On Tue, Aug 07, 2007 at 12:44:55AM -0700, Andrew Morton wrote:
> On Tue, 7 Aug 2007 00:24:37 -0700 Andrew Morton <akpm@...ux-foundation.org> wrote:
> 
> > > Andrew, I really don't want to change the PCI core to handle this, as we
> > > finally fixed a lot of issues with drivers trying to walk these lists
> > > from interrupt context.  So if you want to just hide the warning message
> > > as we are shutting down, that's fine with me.  Or just don't do the
> > > fixups.  But grabbing a reference to the pci device is unsafe in my
> > > opinion and I do not want to do that.
> > > 
> > 
> > OK, good decision ;)
> > 
> > One approach would be for some brave soul to pick his way through
> > the reboot code and ensure that we are correctly and reliably setting
> > system_state to SYSTEM_RESTART, then test that in __might_sleep().
> > 
> > But this does suppress somewhat-useful debugging just because of sysrq-B
> > and I really wouldn't want to utilise the horrid system_state any more that
> > we are presently doing.  I think on balance that it would be better if we
> > could do something more targetted, like modify emergency_restart() to test
> > in_interrupt() and to then apologetically set some well-named global flag
> > which will shut up __might_sleep().  Pretty foul, but I can't think of
> > anything better.
> 
> ok, this might be better.  How about we just stop calling mach_reboot_fixups()
> at sysrq-B time?

Fine with me, but what hardware will be messed up because of this?

thanks,

greg k-h
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