[dpdk-dev] [PATCH] malloc: fix memory element size in case of padding
Thomas Monjalon
thomas at monjalon.net
Tue Nov 26 14:30:16 CET 2019
26/11/2019 13:57, Burakov, Anatoly:
> On 25-Nov-19 11:24 PM, Thomas Monjalon wrote:
> > 21/11/2019 16:14, Burakov, Anatoly:
> >> On 21-Nov-19 2:25 PM, Xueming Li wrote:
> >>> This patch fixes wrong inner memory element size when joining two
> >>> elements.
> >>>
> >>> Fixes: af75078fece3 ("first public release")
> >>> Cc: stable at dpdk.org
> >>>
> >>> Signed-off-by: Xueming Li <xuemingl at mellanox.com>
> >>> ---
> >>> --- a/lib/librte_eal/common/malloc_elem.c
> >>> +++ b/lib/librte_eal/common/malloc_elem.c
> >>> @@ -487,6 +487,10 @@ join_elem(struct malloc_elem *elem1, struct malloc_elem *elem2)
> >>> else
> >>> elem1->heap->last = elem1;
> >>> elem1->next = next;
> >>> + if (elem1->pad) {
> >>> + struct malloc_elem *inner = RTE_PTR_ADD(elem1, elem1->pad);
> >>> + inner->size = elem1->size - elem1->pad;
> >>> + }
> >>> }
> >>
> >> Reviewed-by: Anatoly Burakov <anatoly.burakov at intel.com>
> >
> > I don't understand this patch.
> > The variable inner is never used.
> > What am I missing?
> >
>
> For padded elements, malloc element has two headers - the "outer" header
> with empty space after it, and the "inner" header, after which the user
> memory actually starts. This makes it so that, when joining elements, if
> the outer element had a pad, we also update the inner element size to match.
Where the variable "inner" is used in this function?
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