Re: [PATCH] Improve pci_alloc_consistent wrapper on preemptive kernels

[Takashi Iwai <tiwai@suse.de>]

At Fri, 30 Jul 2004 20:47:21 +0200,
I wrote:
> 
> At Fri, 30 Jul 2004 14:07:57 -0400,
> Jeff Garzik wrote:
> > 
> > Andi Kleen wrote:
> > > On Fri, 30 Jul 2004 13:16:28 -0400
> > > Jeff Garzik <jgarzik@pobox.com> wrote:
> > > 
> > > 
> > > 
> > >>1) Changing from GFP_ATOMIC to <something else> may break code
> > > 
> > > 
> > > x86-64 did it for a long time and I am not aware of problems with it
> > > (however I don't know how widespread CONFIG_PREEMPT use on x86-64 is) 
> > > 
> > > 
> > >>2) Conversely from #1, I also worry why GFP_ATOMIC would be needed at 
> > >>all.  I code all my drivers to require that pci_alloc_consistent() be 
> > >>called from somewhere that is allowed to sleep.
> > > 
> > > 
> > > Maybe you do, but others don't.
> > 
> > Certainly.  Therefore, changing from GFP_ATOMIC will increase likelihood 
> > of breakage, no?
> 
> pci_alloc_consistent() was GFP_ATOMIC only on 2.4 anyway, so I don't
> expect there would be any breakage...

Sorry got confused.  Forget my comment above.  The patch won't
break, of course (although I don't see much gain by it).

Well, I see now the necessity of this patch - pci_alloc_consistent()
is still used in so many drivers...  Maybe we can clean up with a
script?


Takashi