On 8/18/23 12:49, David Laight wrote:
From: Przemek Kitszel
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Sent: Friday, August 18, 2023 11:28 AM
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I'm not sure you should be forcing the memset() either.
This already got discussed: better to fail safe.
Perhaps call it DEFINE_FLEX_Z() to make this clear and
give the option for a non-zeroing version later.
Not everyone wants the expense of zeroing everything.
per Kees, zeroing should be removed by compiler when not needed:
https://lore.kernel.org/intel-wired-lan/202308101128.C4F0FA235@keescook/ (local)
Expect in the most trivial cases the compiler is pretty much never
going to remove the zeroing of the data[] part.
I'm also not at all sure what happens if there is a function
call between the initialisation and any assignments.
With a bit of effort you should be able to pass the '= {}'
through into an inner #define.
Possibly with the alternative of a caller-provider
'= { .obj = call_supplied_initialiser }'
The 'not _Z' form would pass an empty argument.
David
Thanks, makes sense, there could be also DEFINE_FLEX_COUNTED
(or DEFINE_FLEX_BOUNDED) to cover Kees's __counted_by() cases.
Would you like me to cover/convert any existing code/use cases (as with other patches in the series, to have some examples/actual usage of newly introduced macros)?
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