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SubjectRe: ide: indeed, using list_for_each_entry_safe removes endless looping / hang [Was: Re: 2.5.65-ac2 -- hda/ide trouble on ICH4]

On Mon, 24 Mar 2003, Alexander Atanasov wrote:
> Hello, Alan!
>
> On 24 Mar 2003 17:40:08 +0000
> Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
>
> > On Mon, 2003-03-24 at 16:01, Alexander Atanasov wrote:
> > > I don't understand, what's the difference and how the list is
> > > lost?
> > > ata_unused used to hold all drives that were not claimed by any
> > > driver, now idedefault_driver claims all that drives, all drives go
> > > in the .list
> >
> > ata_unused -> unattached device slots, new hotplug discoveries
>
> Ok.
>
> > idedefault_driver -> attached/known devices with no driver
> > other list -> driven by that driver
> >
> > > The bug is there, and waiting to explode, keeping both lists would
> > > mean to add one more list head in ide_drive_t, is that the fix
> > > you want?
> >
> > I don't see where stuff is ending up on both lists yet. I've not had
> > time to look hard at it though
> >
>
> It happens this way:
> ide_register_driver -> ata_attach -> idedefault_driver.attach -> ide_register_subdriver -> list_add(&driver->list, &driver->drives) ->
> return to ata_attach -> list_add_tail(&drive->list, &ata_unused);

Exactly.

Alan, if we want to keep ata_unused, we should remove
list_add_tail(%drive->list, &ata_unused) from ata_attach()
and perhaps use (after fixing it to handle idedefault_driver)
ide_replace_subdriver() for driver switching for drives owned
by idedefault_driver.

BTW in ide_register_driver() we don't use ide_drives lock to protect
drive->list changes, why?

--
bzolnier

> --
> have fun,
> alex
>

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