Re: [dpdk-dev] [PATCH 2/2] mempool: fix unsafe tailq element removal

[Olivier Matz <olivier.matz@6wind.com>]

Hi Sergio,

On 07/22/2016 06:01 PM, Sergio Gonzalez Monroy wrote:
> Potentially user provided function could remove/free tailq elements.
> Doing so within a TAILQ_FOREACH loop is not safe.
> 
> Use _SAFE versions of _FOREACH macros.
> 
> Signed-off-by: Sergio Gonzalez Monroy <sergio.gonzalez.monroy@intel.com>
> ---
>  lib/librte_mempool/rte_mempool.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
> index 8806633..394154a 100644
> --- a/lib/librte_mempool/rte_mempool.c
> +++ b/lib/librte_mempool/rte_mempool.c
> @@ -157,10 +157,10 @@ rte_mempool_obj_iter(struct rte_mempool *mp,
>  	rte_mempool_obj_cb_t *obj_cb, void *obj_cb_arg)
>  {
>  	struct rte_mempool_objhdr *hdr;
> -	void *obj;
> +	void *obj, *temp;
>  	unsigned n = 0;
>  
> -	STAILQ_FOREACH(hdr, &mp->elt_list, next) {
> +	STAILQ_FOREACH_SAFE(hdr, &mp->elt_list, next, temp) {
>  		obj = (char *)hdr + sizeof(*hdr);
>  		obj_cb(mp, obj_cb_arg, obj, n);
>  		n++;
> @@ -176,8 +176,9 @@ rte_mempool_mem_iter(struct rte_mempool *mp,
>  {
>  	struct rte_mempool_memhdr *hdr;
>  	unsigned n = 0;
> +	void *temp;
>  
> -	STAILQ_FOREACH(hdr, &mp->mem_list, next) {
> +	STAILQ_FOREACH_SAFE(hdr, &mp->mem_list, next, temp) {
>  		mem_cb(mp, mem_cb_arg, hdr, n);
>  		n++;
>  	}

Not sure it is required to use the _SAFE() variant here.
The object or mem_chunk should be considered as const, because these
objects are not allocated/freed by the user but by the mempool functions.

> @@ -1283,12 +1284,13 @@ void rte_mempool_walk(void (*func)(struct rte_mempool *, void *),
>  {
>  	struct rte_tailq_entry *te = NULL;
>  	struct rte_mempool_list *mempool_list;
> +	void *temp;
>  
>  	mempool_list = RTE_TAILQ_CAST(rte_mempool_tailq.head, rte_mempool_list);
>  
>  	rte_rwlock_read_lock(RTE_EAL_MEMPOOL_RWLOCK);
>  
> -	TAILQ_FOREACH(te, mempool_list, next) {
> +	TAILQ_FOREACH_SAFE(te, mempool_list, next, temp) {
>  		(*func)((struct rte_mempool *) te->data, arg);
>  	}
>  
> 

I think this one is legitimate and we should have it for 16.07.
So only this hunk would be required, and the patch 1/2 may be dropped if
we remove the first 2 chunks.

Regards,
Olivier