Re: [PATCH 1/2] ixgbe: fix setup of mbuf initializer template

[Bruce Richardson <bruce.richardson-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>]

On Thu, Dec 04, 2014 at 03:26:20PM +0100, Jean-Mickael Guerin wrote:
> Add a compiler barrier to make sure all fields covered by
> the marker rearm_data are assigned before the read.
> 
> Signed-off-by: Jean-Mickael Guerin <jean-mickael.guerin-pdR9zngts4EAvxtiuMwx3w@public.gmane.org>
> Acked-by: David Marchand <david.marchand-pdR9zngts4EAvxtiuMwx3w@public.gmane.org>
> Fixes: 0ff3324da2 ("ixgbe: rework vector pmd following mbuf changes")

Acked-by: Bruce Richardson <bruce.richardson-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>

> ---
>  lib/librte_pmd_ixgbe/ixgbe_rxtx_vec.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/lib/librte_pmd_ixgbe/ixgbe_rxtx_vec.c b/lib/librte_pmd_ixgbe/ixgbe_rxtx_vec.c
> index 579bc46..c1b5a78 100644
> --- a/lib/librte_pmd_ixgbe/ixgbe_rxtx_vec.c
> +++ b/lib/librte_pmd_ixgbe/ixgbe_rxtx_vec.c
> @@ -739,6 +739,9 @@ ixgbe_rxq_vec_setup(struct igb_rx_queue *rxq)
>  	mb_def.buf_len = rxq->mb_pool->elt_size - sizeof(struct rte_mbuf);
>  	mb_def.port = rxq->port_id;
>  	rte_mbuf_refcnt_set(&mb_def, 1);
> +
> +	/* prevent compiler reordering: rearm_data covers previous fields */
> +	rte_compiler_barrier();
>  	rxq->mbuf_initializer = *((uint64_t *)&mb_def.rearm_data);
>  	return 0;
>  }
> -- 
> 2.1.3
>