Re: [dpdk-dev] [PATCH] malloc: fix memory element size in case of padding

[Thomas Monjalon <thomas@monjalon.net>]

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@dpdk.org
> >>>
> >>> Signed-off-by: Xueming Li <xuemingl@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@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?