On Fri, Jul 13 2007, James Bottomley wrote:
> On Wed, 2007-07-04 at 15:22 +0200, Geert Uytterhoeven wrote:
> > + kaddr = kmap_atomic(sgpnt->page, KM_USER0);
> > + if (!kaddr)
> > + return -1;
> > + len = sgpnt->length;
> > + if ((req_len + len) > buflen) {
> > + active = 0;
> > + len = buflen - req_len;
> > + }
> > + memcpy(kaddr + sgpnt->offset, buf + req_len,
> > len);
> > + kunmap_atomic(kaddr, KM_USER0);
>
> This isn't a SCSI objection, but this sequence appears several times in
> this driver. It's wrong for a non-PIPT architecture (and I believe the
> PS3 is VIPT) because you copy into the kernel alias for the page, which
> dirties the line in the cache of that alias (the user alias cache line
> was already invalidated). However, unless you flush the kernel alias to
> main memory, the user could read stale data. The way this is supposed
> to be done is to do a
>
> flush_kernel_dcache_page(kaddr)
>
> before doing the kunmap.
>
> Otherwise it looks OK from the SCSI point of view.
Well, even worse is that fact that it's using KM_USER0 from interrupt
context.
--
Jens Axboe
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