Re: [dpdk-dev] [PATCH] mempool: don't leak ring on failure

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

Hi Stephen,

> 
> If mempool can not be created because of insufficient memory
> it returns an error but has already created a ring (and leaves it
> behind). This prevents code from trying one mempool size and then
> retrying with a smaller size if the bigger size fails.
> 
> Reordering to do ring creation after getting memory fixes
> the problem.
>

But now, memzone created for the actual mempool could get leaked instead?
 
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> 
> 
> --- a/lib/librte_mempool/rte_mempool.c	2014-06-24 08:20:28.513771717 -0700
> +++ b/lib/librte_mempool/rte_mempool.c	2014-06-24 08:20:28.513771717 -0700
> @@ -473,15 +473,6 @@ rte_mempool_xmem_create(const char *name
> 
>  	rte_rwlock_write_lock(RTE_EAL_MEMPOOL_RWLOCK);
> 
> -	/* allocate the ring that will be used to store objects */
> -	/* Ring functions will return appropriate errors if we are
> -	 * running as a secondary process etc., so no checks made
> -	 * in this function for that condition */
> -	rte_snprintf(rg_name, sizeof(rg_name), RTE_MEMPOOL_MZ_FORMAT, name);
> -	r = rte_ring_create(rg_name, rte_align32pow2(n+1), socket_id, rg_flags);
> -	if (r == NULL)
> -		goto exit;
> -
>  	/*
>  	 * reserve a memory zone for this mempool: private data is
>  	 * cache-aligned
> @@ -542,6 +533,15 @@ rte_mempool_xmem_create(const char *name
>  		startaddr = (void*)addr;
>  	}
> 
> +	/* allocate the ring that will be used to store objects */
> +	/* Ring functions will return appropriate errors if we are
> +	 * running as a secondary process etc., so no checks made
> +	 * in this function for that condition */
> +	rte_snprintf(rg_name, sizeof(rg_name), RTE_MEMPOOL_MZ_FORMAT, name);
> +	r = rte_ring_create(rg_name, rte_align32pow2(n+1), socket_id, rg_flags);
> +	if (r == NULL)
> +		goto exit;
> +
>  	/* init the mempool structure */
>  	mp = startaddr;
>  	memset(mp, 0, sizeof(*mp));