Re: [PATCH v3 1/3] net/usb/r815x: replace USB buffer from stack toDMA-able

From: Joe Perches
Date: Tue Jul 30 2013 - 14:41:29 EST

On Tue, 2013-07-30 at 11:33 -0700, David Miller wrote:
> From: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>
> Date: Tue, 30 Jul 2013 07:00:59 -0700
> > This call is so slow, you can afford to make a call to kmalloc for the
> > data, as it sure just did for other structures it needed :)
> I told him to implement things this way, to avoid calling kmalloc every
> single register access.
> Using kmalloc all the time makes the access fragile, since a badly timed
> call during high memory pressure can fail.
> I'd rather the potential failure happen at one time, probe time.
> In any event, Ming Lei has suggested using usbnet_{read,write}_cmd()
> instead, which sounds like a good solution to this problem.

Those do per-call allocs too.

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