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

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Message-ID: <46B82430.7050200@sw.ru>
Date:	Tue, 07 Aug 2007 11:50:08 +0400
From:	"Denis V. Lunev" <den@...ru>
To:	Greg KH <gregkh@...e.de>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	"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

Greg KH wrote:
> 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?

static struct device_fixup fixups_table[] = {
> > { PCI_VENDOR_ID_CYRIX, PCI_DEVICE_ID_CYRIX_5530_LEGACY,
> > cs5530a_warm_reset },
> > { PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_CS5536_ISA, cs5536_warm_reset },
> > };
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