Re: Sign changes through function signatures

[Tyler Retzlaff <roretzla@linux.microsoft.com>]

On Thu, Feb 02, 2023 at 02:23:39PM -0500, Ben Magistro wrote:
> Hello,
> 
> While making some updates to our code base for 22.11.1 that were missed in
> our first pass through, we hit the numa node change[1].  In the process of
> updating our code, we noticed that a couple functions (rx/tx_queue_setup,
> maybe more that we aren't using) state they accept `SOCKET_ID_ANY` but the
> function signature then asks for an unsigned integer while `SOCKET_ID_ANY`
> is `-1`.  Following it through the redirect to the "real" function it also
> asks for an unsigned integer which is then passed on to one or more
> functions asking for an integer.  As an example using the the i40e driver
> -- we would call `rte_eth_tx_queue_setup` [2] which ultimately calls
> `i40e_dev_tx_queue_setup`[3] which finally calls `rte_zmalloc_socket`[4]
> and `rte_eth_dma_zone_reserve`[5].
> 
> I guess what I am looking for is clarification on if this is intentional or
> if this is additional cleanup that may need to be completed/be desirable so
> that signs are maintained through the call paths and avoid potentially
> producing sign-conversion warnings.  From the very quick glance I took at
> the i40e driver, it seems these are just passed through to other functions
> and no direct use/manipulation occurs (at least in the mentioned functions).

i believe this is just sloppyness with sign in our api surface. i too
find it frustrating that use of these api force either explicit
casts or suffer having to suppress warnings.

in the past examples of this have been cleaned up without full deprecation
notices but there are a lot of instances. i also feel (unpopular opinion)
that for some integer types like this that have constrained range / number
spaces it would be of value to introduce a typedef that can be used
consistently.

for now you'll just have to add the casts and hopefully in the future we
will fix the api making them unnecessary. of course feel free to submit
patches too, it would be great to have these cleaned up.

> 
> 1)
> https://patches.dpdk.org/project/dpdk/patch/20221004145850.32331-1-olivier.matz@6wind.com/
> 2)
> https://doc.dpdk.org/api/rte__ethdev_8h.html#a796c2f20778984c6f41b271e36bae50e
> 3) https://github.com/DPDK/dpdk/blob/main/drivers/net/i40e/i40e_rxtx.c#L1949
> 4)
> https://doc.dpdk.org/api/rte__malloc_8h.html#a7e9f76b7e0b0921a617c6ab8b28f53b3
> 5)
> https://github.com/DPDK/dpdk/blob/1094dd940ec0cc4e3ce2c5cd94807350855a17f9/lib/ethdev/ethdev_driver.h#L1566