Messages in this thread | | | Date | Wed, 22 Jul 2015 12:46:24 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH V3] x86/mm/pat: Do a small optimization and fix in reserve_memtype |
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On Wed, Jul 22, 2015 at 05:06:04PM +0800, Pan Xinhui wrote: > how about: > memtype_lock protects the rb-tree root and the rb-nodes which is a field of memtype from delete/add/lookup in a race.
Use this:
"All pat_rbtree operations need to be performed while holding the memtype_lock."
> Actually I have same questions. I find these output logs are added in > commit: 6997ab4982a29925e79f72c3a59823cf944c3529(x86: add PAT related > debug prints) In the past, *new_type == actual_type == new->type on > success. codes are below. author use actual_type there.
So this function is one bit PITA. So req_type is used to compute actual type a bit higher:
actual_type = pat_x_mtrr_type(start, end, req_type);
and from then on actual_type is being used.
BUT!, in order to have *all* debugging information, the last dprintk() call should dump actual_type and req_type because this way we show what pat_x_mtrr_type() did too. And we don't need to dump new->type because this is the !err case and in that case we assigned new_type to it, which we dump already.
Ok?
Btw, you could also simplify this:
if (is_range_ram == 1) {
err = reserve_ram_pages_type(start, end, req_type, new_type);
return err; }
to:
if (is_range_ram == 1) return reserve_ram_pages_type(start, end, req_type, new_type);
while at it.
Thanks.
-- Regards/Gruss, Boris.
ECO tip #101: Trim your mails when you reply. --
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