Re: [dpdk-dev] [PATCH v11 2/6] app/testpmd: add multiple pools per core creation

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 10/16/2020 2:39 PM, Viacheslav Ovsiienko wrote:
> The command line parameter --mbuf-size is updated, it can handle
> the multiple values like the following:
> 
> --mbuf-size=2176,512,768,4096
> 
> specifying the creation the extra memory pools with the requested
> mbuf data buffer sizes. If some buffer split feature is engaged
> the extra memory pools can be used to configure the Rx queues
> with rte_the_dev_rx_queue_setup_ex().
> 
> The extra pools are created with requested sizes, and pool names
> are assigned with appended index: mbuf_pool_socket_%socket_%index.
> Index zero is used to specify the first mandatory pool to maintain
> compatibility with existing code.
> 
> Signed-off-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>

<...>

>   /* Mbuf Pools */
>   static inline void
> -mbuf_poolname_build(unsigned int sock_id, char* mp_name, int name_size)
> +mbuf_poolname_build(unsigned int sock_id, char *mp_name,
> +		    int name_size, unsigned int idx)
>   {
> -	snprintf(mp_name, name_size, "mbuf_pool_socket_%u", sock_id);
> +	if (!idx)
> +		snprintf(mp_name, name_size, "mbuf_pool_socket_%u", sock_id);
> +	else
> +		snprintf(mp_name, name_size, "mbuf_pool_socket_%u_%u",
> +			 sock_id, idx);

'mp_name' can theoretically overflow and gives a compiler warning, although not 
sure if this truncation is a problem in practice.

../app/test-pmd/testpmd.c: In function ‘rx_queue_setup’:
../app/test-pmd/testpmd.h:666:53: error: ‘%u’ directive output may be truncated 
writing between 1 and 10 bytes into a region of size between 0 and 7 
[-Werror=format-truncation=]
  666 |   snprintf(mp_name, name_size, "mbuf_pool_socket_%u_%u",
      |                                                     ^~
../app/test-pmd/testpmd.h:666:32: note: directive argument in the range [1, 
4294967295]
   666 |   snprintf(mp_name, name_size, "mbuf_pool_socket_%u_%u",
       |                                ^~~~~~~~~~~~~~~~~~~~~~~~
../app/test-pmd/testpmd.h:666:3: note: ‘snprintf’ output between 21 and 39 bytes 
into a destination of size 26
   666 |   snprintf(mp_name, name_size, "mbuf_pool_socket_%u_%u",
       |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   667 |     sock_id, idx);
       |     ~~~~~~~~~~~~~

Any suggestion for fix? Can we shorten the string above, is it used somewhere 
else? Or casting variables to a smaller size may work too..