Re: [patch] drivers: wait for threaded probes between initcall levels

[Grant Grundler <grundler@parisc-linux.org>]

On Fri, Oct 27, 2006 at 04:06:26PM -0700, Andrew Morton wrote:
> On Fri, 27 Oct 2006 23:59:30 +0100
> Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
> 
> > Ar Gwe, 2006-10-27 am 11:42 -0700, ysgrifennodd Andrew Morton:
> > > IOW, we want to be multithreaded _within_ an initcall level, but not between
> > > different levels.
> > 
> > Thats actually insufficient. We have link ordered init sequences in
> > large numbers of driver subtrees (ATA, watchdog, etc). We'll need
> > several more initcall layers to fix that.
> > 
> 
> It would be nice to express those dependencies in some clearer and less
> fragile manner than link order.  I guess finer-grained initcall levels
> would do that, but it doesn't scale very well.

Would making use of depmod data be a step in the right direction?
ie nic driver calls extern function (e.g. pci_enable_device())
and therefore must depend on module which provides that function.

My guess is this probably isn't 100% sufficient to replace all initcall
levels.  But likely sufficient within a given initcall level.
My main concern are circular dependencies (which are rare).

> But whatever.  I think multithreaded probing just doesn't pass the
> benefit-versus-hassle test, sorry.   Make it dependent on CONFIG_GREGKH ;)

Isn't already? :)

I thought parallel PCI and SCSI probing on system with multiple NICs and
"SCSI" storage requires udev to create devices with consistent naming.

thanks,
grant
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