Re: [dpdk-dev] [dpdk-stable] [PATCH v3] ethdev: fix data type for port id

[Stephen Hemminger <stephen@networkplumber.org>]

On Tue, 03 Nov 2020 19:44:21 +0100
Thomas Monjalon <thomas@monjalon.net> wrote:

> 02/11/2020 10:18, wangyunjian:
> > From: Yunjian Wang <wangyunjian@huawei.com>
> > 
> > The ethdev port id is 16 bits now. This patch fixes the data type
> > of the variable for 'pid', which changing from uint32_t to uint16_t.
> > 
> > RTE_MAX_ETHPORTS is the maximum number of ports, which customized by
> > the user. To avoid 16-bit unsigned integer overflow, the valid value
> > of RTE_MAX_ETHPORTS should be set from 0 to UINT16_MAX, and it is
> > safer to cut one more port from space.
> > 
> > So we use RTE_BUILD_BUG_ON() to ensure that RTE_MAX_ETHPORTS is less
> > to UINT16_MAX.
> > 
> > Fixes: 5b7ba31148a8 ("ethdev: add port ownership")
> > Cc: stable@dpdk.org
> > 
> > Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
> > ---
> > v3:
> >    fix code styles suggested by Thomas Monjalon and Andrew Rybchenko  
> 
> I don't understand why you add the compile check in several place.
> We should just find one good place for checking RTE_MAX_ETHPORTS
> at compilation time.
> 
> I suggest rte_eth_find_next() or rte_eth_dev_allocate().
> Or maybe rte_eth_dev_is_valid_port().
> 
> Please choose only one.
> 
> 

That was my reaction, check once.
It doesn't even need to be inside a function, it can be anywhere.