Re: [PATCH v2 net-next 1/7] bpf: add 'flags' attribute to BPF_MAP_UPDATE_ELEM command

[Hannes Frederic Sowa]

On Do, 2014-11-13 at 17:36 -0800, Alexei Starovoitov wrote:
> the current meaning of BPF_MAP_UPDATE_ELEM syscall command is:
> either update existing map element or create a new one.
> Initially the plan was to add a new command to handle the case of
> 'create new element if it didn't exist', but 'flags' style looks
> cleaner and overall diff is much smaller (more code reused), so add 'flags'
> attribute to BPF_MAP_UPDATE_ELEM command with the following meaning:
>  #define BPF_ANY	0 /* create new element or update existing */
>  #define BPF_NOEXIST	1 /* create new element if it didn't exist */
>  #define BPF_EXIST	2 /* update existing element */

Would a cmpxchg-alike function be handy here?

Bye,
Hannes


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