Hrm... since a devrequest structure is needed by anyone who wants to do a
control request, and most of the uses seem to be "allocate, use, destroy",
would a slab cache be useful here?  I mean a USB-wide one, not a
per-sub-driver one.

Matt

On Tue, Dec 11, 2001 at 03:14:22PM -0500, Johannes Erdfelt wrote:
> On Tue, Dec 11, 2001, David Brownell <[EMAIL PROTECTED]> wrote:
> > > All of the USB host controller drivers are PCI devices.
> > 
> > Various folk have said they want to integrate patches
> > for some of those non-PCI OHCIs in the 2.5 tree, so I'd
> > expect that to change.
> > 
> > Re the original patch, I think that's a case of "better safe
> > than sorry".  Not DMAing to/from the stack is a general
> > rule for the whole kernel, not just USB.
> 
> I seem to recall Alan Cox mentioning that it's not guaranteed to be safe
> in any kernel since some architectures will move to a non DMA capable
> stack.
> 
> IMHO, since the only safe thing to do across all architectures is to
> kmalloc the devrequest structure, anything other than that is essentially
> micro optimization that's not worth it.
> 
> JE
> 
> 
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-- 
Matthew Dharm                              Home: [EMAIL PROTECTED] 
Maintainer, Linux USB Mass Storage Driver

Oh BAY-bee.
                                        -- Dust Puppy to Greg
User Friendly, 12/13/1997

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