Re: [dpdk-dev] [PATCH 1/1] eal/linux: do not create user mem map repeatedly when it exists

["Burakov, Anatoly" <anatoly.burakov@intel.com>]

On 16-Jul-20 2:38 PM, wangyunjian wrote:
> From: Yunjian Wang <wangyunjian@huawei.com>
> 
> Currently, we will create new user mem map entry for the same memory
> segment, but in fact it has already been added to the user mem maps.
> It's not necessary to create it twice.
> 
> Fixes: 0cbce3a167f1 ("vfio: skip DMA map failure if already mapped")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
> ---
>   lib/librte_eal/linux/eal_vfio.c | 7 +++++++
>   1 file changed, 7 insertions(+)
> 
> diff --git a/lib/librte_eal/linux/eal_vfio.c b/lib/librte_eal/linux/eal_vfio.c
> index abb12a354..d8a8c39ab 100644
> --- a/lib/librte_eal/linux/eal_vfio.c
> +++ b/lib/librte_eal/linux/eal_vfio.c
> @@ -1828,6 +1828,13 @@ container_dma_map(struct vfio_config *vfio_cfg, uint64_t vaddr, uint64_t iova,
>   		ret = -1;
>   		goto out;
>   	}
> +
> +	/* we don't need create new user mem map entry
> +	 * for the same memory segment.
> +	 */
> +	if (errno == EBUSY || errno == EEXIST)
> +		goto out;
> +

I'm not sure i understand this patch. If we get errno, the call has 
failed, which means we're doing "goto out" from a few lines above. Am i 
missing something here?

>   	/* create new user mem map entry */
>   	new_map = &user_mem_maps->maps[user_mem_maps->n_maps++];
>   	new_map->addr = vaddr;
> 


-- 
Thanks,
Anatoly