RE: [PATCH 2/4] net: make sockptr_is_null strict aliasing safe

[Jan Engelhardt]

On Wednesday 2020-07-29 10:04, David Laight wrote:
>From: Christoph Hellwig <h...@lst.de>
>> Sent: 28 July 2020 17:39
>> 
>> While the kernel in general is not strict aliasing safe we can trivially
>> do that in sockptr_is_null without affecting code generation, so always
>> check the actually assigned union member.
>
>Even with 'strict aliasing' gcc (at least) guarantees that
>the members of a union alias each other.
>It is about the only way so safely interpret a float as an int.

The only?

  float given;
  int i;
  memcpy(&i, &given, sizeof(i));
  BUILD_BUG_ON(sizeof(i) > sizeof(given));