Re: [dpdk-dev] [PATCH] mempool: fix sp sc mempool bug

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

Hi Weiliang,

On 09/08/2016 05:36 AM, Weiliang Luo wrote:
> Signed-off-by: Weiliang Luo <droidluo@gmail.com>
> ---
>  lib/librte_mempool/rte_mempool.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
> index 2e28e2e..350d77a 100644
> --- a/lib/librte_mempool/rte_mempool.c
> +++ b/lib/librte_mempool/rte_mempool.c
> @@ -879,7 +879,7 @@ rte_mempool_create(const char *name, unsigned n, unsigned elt_size,
>  	 * Since we have 4 combinations of the SP/SC/MP/MC examine the flags to
>  	 * set the correct index into the table of ops structs.
>  	 */
> -	if (flags & (MEMPOOL_F_SP_PUT | MEMPOOL_F_SC_GET))
> +	if ((flags & MEMPOOL_F_SP_PUT) && (flags & MEMPOOL_F_SC_GET))
>  		rte_mempool_set_ops_byname(mp, "ring_sp_sc", NULL);
>  	else if (flags & MEMPOOL_F_SP_PUT)
>  		rte_mempool_set_ops_byname(mp, "ring_sp_mc", NULL);
> 


I would just change the title and add some explanation in the commit
log. I suggest:

"""
mempool: fix corruption due to invalid handler

When using rte_mempool_create(), the mempool handler is selected
depending on the flags given by the user:
  - multi-consumer / multi-producer
  - multi-consumer / single-producer
  - single-consumer / multi-producer
  - single-consumer / single-producer

The flags were not properly tested, resulting in the selection of sc/sp
handler if sc/mp or mc/sp was asked. This can lead to corruption or
crashes because the get/put operations are not atomic.

Fixes: 449c49b93a6b ("mempool: support handler operations")

Signed-off-by: Weiliang Luo <droidluo@gmail.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>
"""


Thanks!
Olivier