From ca2e1a627035002cd33d9667431e80bad90c25fa Mon Sep 17 00:00:00 2001 From: Maciej Fijalkowski Date: Thu, 7 Jul 2022 15:08:42 +0200 Subject: xsk: Mark napi_id on sendmsg() When application runs in busy poll mode and does not receive a single packet but only sends them, it is currently impossible to get into napi_busy_loop() as napi_id is only marked on Rx side in xsk_rcv_check(). In there, napi_id is being taken from xdp_rxq_info carried by xdp_buff. From Tx perspective, we do not have access to it. What we have handy is the xsk pool. Xsk pool works on a pool of internal xdp_buff wrappers called xdp_buff_xsk. AF_XDP ZC enabled drivers call xp_set_rxq_info() so each of xdp_buff_xsk has a valid pointer to xdp_rxq_info of underlying queue. Therefore, on Tx side, napi_id can be pulled from xs->pool->heads[0].xdp.rxq->napi_id. Hide this pointer chase under helper function, xsk_pool_get_napi_id(). Do this only for sockets working in ZC mode as otherwise rxq pointers would not be initialized. Signed-off-by: Maciej Fijalkowski Signed-off-by: Daniel Borkmann Acked-by: Magnus Karlsson Link: https://lore.kernel.org/bpf/20220707130842.49408-1-maciej.fijalkowski@intel.com --- net/xdp/xsk.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'net/xdp') diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c index 09002387987e..5b4ce6ba1bc7 100644 --- a/net/xdp/xsk.c +++ b/net/xdp/xsk.c @@ -639,8 +639,11 @@ static int __xsk_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len if (unlikely(need_wait)) return -EOPNOTSUPP; - if (sk_can_busy_loop(sk)) + if (sk_can_busy_loop(sk)) { + if (xs->zc) + __sk_mark_napi_id_once(sk, xsk_pool_get_napi_id(xs->pool)); sk_busy_loop(sk, 1); /* only support non-blocking sockets */ + } if (xs->zc && xsk_no_wakeup(sk)) return 0; -- cgit v1.2.3