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Date: Tue, 12 Apr 2016 17:06:36 +0200
From: Olivier MATZ <olivier.matz@6wind.com>
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To: Christian Ehrhardt <christian.ehrhardt@canonical.com>, 
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Subject: Re: [dpdk-dev] [PATCH] lpm: fix freeing of rules_tbl in
	rte_lpm_free_v20
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Hi,

On 04/12/2016 03:49 PM, Christian Ehrhardt wrote:
> Back then when we fixed the missing free lpm I was to quickly to say yes
> if it applies not only to the lpm6 but also to all of the lpm code.
>
> It turned out to not apply to all of them. In rte_lpm_create_v20 there
> is an unexpected fused allocation:
> mem_size = sizeof(*lpm) + (sizeof(lpm->rules_tbl[0]) * max_rules);
> [...]
> lpm = (struct rte_lpm_v20 *)rte_zmalloc_socket(mem_name,mem_size,
>                 RTE_CACHE_LINE_SIZE, socket_id);
>
> That causes lpm->rules_tbl not to have an own struct malloc_elem that
> can be derived via RTE_PTR_SUB(data, MALLOC_ELEM_HEADER_LEN) in
> malloc_elem_from_data.
> Due to that the rte_lpm_free_v20 accidentially misderives the elem and
> assumes it is ELEM_FREE triggering in malloc_elem_free
> if (!malloc_elem_cookies_ok(elem) || elem->state !=
>          return -1;
>
> While it seems counter-intuitive the way to properly remove rules_tbl in
> the old fused allocation style of rte_lpm_free_v20 is to not remove it.
>
> The newer rte_lpm_free_v1604 is safe because in rte_lpm_create_v1604
> rules_tbl is a separate allocation.
>
> Fixes: d4c18f0a1d5d ("lpm: fix missing free")
>
> Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>

Acked-by: Olivier Matz <olivier.matz@6wind.com>

Thanks, I missed it too during the review.