[PATCH v2 8/9] bpf: make callback handle atomic with relaxed access

[Marat Khalili]

On 19/10/2026 22:27, Konstantin Ananyev wrote:
>> The callback handle member cb of struct bpf_eth_cbi is concurrently
>> cleared by the control plane on unload and read by the datapath to
>> decide whether to execute the BPF filter program. Without atomic typing,
>> this concurrent access constitutes a data race in the C11 memory model,
> Hmm... why is that?
> So far, I don't see any.
> Can you probably point where you believe is a data-race, and how using 
> atomic
> load/store can prevent it.

It follows from the standard (5.1.2.4 Multi-threaded executions and data 
races):

     Two expression evaluations conflict if one of them modifies a 
memory location and the
     other one reads or modifies the same memory location. [...]

     The execution of a program contains a data race if it contains two 
conflicting actions in
     different threads, at least one of which is not atomic, and neither 
happens before the
     other. Any such data race results in undefined behavior.