Marco <ctxspi@xxxxxxxxx> writes:
> Hi
>
> Assuming to have this struct:
>
> struct hash_elem {
> int cnt;
> };
>
> and kernel space program want read cnt value:
>
> struct hash_elem *val = bpf_map_lookup_elem(&hash_map, &key);
>
> if (val)
> {
>
> # time fraction
>
> bpf_printk("My value %d", val->cnt);
> }
>
> What happens if the hash_map is a pinned map and in the same time
> space of 'time fraction" a user program deletes the element of the
> key?
> What happen at val pointer?
The val pointer is RCU-protected so it will stick around until the end
of your BPF program's execution. However, it's up to your own code to
protect against concurrent *updates* of the value...
-Toke
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