On 2019/01/17 21:39, Jason Wang wrote: > On 2019/1/17 下午7:20, Toshiaki Makita wrote: >> When napi_tx is enabled, virtnet_poll_cleantx() called >> free_old_xmit_skbs() even for xdp send queue. >> This is bogus since the queue has xdp_frames, not sk_buffs, thus mangled >> device tx bytes counters because skb->len is meaningless value, and even >> triggered oops due to general protection fault on freeing them. >> >> Since xdp send queues do not aquire locks, old xdp_frames should be >> freed only in virtnet_xdp_xmit(), so just skip free_old_xmit_skbs() for >> xdp send queues. >> >> Similarly virtnet_poll_tx() called free_old_xmit_skbs(). This NAPI >> handler is called even without calling start_xmit() because cb for tx is >> by default enabled. Once the handler is called, it enabled the cb again, >> and then the handler would be called again. We don't need this handler >> for XDP, so don't enable cb as well as not calling free_old_xmit_skbs(). >> >> Also, we need to disable tx NAPI when disabling XDP, so >> virtnet_poll_tx() can safely access curr_queue_pairs and >> xdp_queue_pairs, which are not atomically updated while disabling XDP. > > > I suggest to split this into another patch or squash this part to patch 1.
This part is for invocation of is_xdp_raw_buffer_queue() from virtnet_poll_tx(), which is added in this patch, so I'm thinking it's more natural to keep this hunk in this patch. -- Toshiaki Makita
