Re: [dpdk-stable] [dpdk-dev] [PATCH v3 1/3] net/sfc: fix power of 2 round up when align has smaller type

[Andrew Rybchenko <arybchenko@solarflare.com>]

On 7/24/19 7:57 PM, Ferruh Yigit wrote:
> On 7/24/2019 2:16 PM, Andrew Rybchenko wrote:
>> Substitute driver-defined P2ROUNDUP() h with EFX_P2ROUNDUP()
>> defined in libefx.
>>
>> Cast value and alignment to one specified type to guarantee result
>> correctness.
>>
>> Fixes: e1b944598579 ("net/sfc: build libefx")
>> Cc: stable@dpdk.org
>>
>> Signed-off-by: Andrew Rybchenko <arybchenko@solarflare.com>
> <...>
>
>> @@ -29,6 +29,10 @@ extern "C" {
>>   /* The macro expands divider twice */
>>   #define	EFX_DIV_ROUND_UP(_n, _d)		(((_n) + (_d) - 1) / (_d))
>>   
>> +/* Round value up to the nearest power of two. */
>> +#define	EFX_P2ROUNDUP(_type, _value, _align)	\
>> +	(-(-(_type)(_value) & -(_type)(_align)))
>> +
> I trust you it does what it says J
>
> Just a high level comment, should we have some kind of tools/utilities file in
> one of the libraries so everyone can use/share them?

It is the base driver code and it is used in the base driver, so it can't
rely on any DPDK library. There are RTE_ALIGN_FLOOR/CEIL in
lib/librte_eal/common/include/rte_common.h.

Before the patch the macro was defined in efsys.h (i.e. driver specific
and could use defines available for the driver), but in fact it was
duplicated in too many drivers and we decided to have it in libefx
(base driver in DPDK case) itself.