On Wed, 24 Jul 2024 01:46:11 +0200 Maciej Fijalkowski wrote: > Goal of this commit was to prevent compiler from code reoder such as NAPI > is launched before update of xsk_buff_pool pointer which is achieved with > WRITE_ONCE()/synchronize_net() pair. Then per my understanding single > READ_ONCE() within NAPI was sufficient, the one that makes the decision > which Rx routine should be called (zc or standard one). Given that bh are > disabled and updater respects RCU grace period IMHO pointer is valid for > current NAPI cycle. So if we are already in the af_xdp handler, and update patch sets pool to NULL - the af_xdp handler will be fine with the pool becoming NULL? I guess it may be fine, it's just quite odd to call the function called _ONCE() multiple times..
