From ea7137ae213c51a3df3fb0fa27a713a8b932f639 Mon Sep 17 00:00:00 2001 From: Magnus Karlsson Date: Fri, 18 Dec 2020 14:45:25 +0100 Subject: [PATCH] xsk: Rollback reservation at NETDEV_TX_BUSY MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Rollback the reservation in the completion ring when we get a NETDEV_TX_BUSY. When this error is received from the driver, we are supposed to let the user application retry the transmit again. And in order to do this, we need to roll back the failed send so it can be retried. Unfortunately, we did not cancel the reservation we had made in the completion ring. By not doing this, we actually make the completion ring one entry smaller per NETDEV_TX_BUSY error we get, and after enough of these errors the completion ring will be of size zero and transmit will stop working. Fix this by cancelling the reservation when we get a NETDEV_TX_BUSY error. Fixes: dedf51134337 ("xsk: Do not discard packet when NETDEV_TX_BUSY") Reported-by: Xuan Zhuo Signed-off-by: Magnus Karlsson Signed-off-by: Daniel Borkmann Acked-by: Björn Töpel Link: https://lore.kernel.org/bpf/20201218134525.13119-3-magnus.karlsson@gmail.com --- net/xdp/xsk.c | 3 +++ net/xdp/xsk_queue.h | 5 +++++ 2 files changed, 8 insertions(+) diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c index d531f9cd0de6a..8037b04a9edd1 100644 --- a/net/xdp/xsk.c +++ b/net/xdp/xsk.c @@ -487,6 +487,9 @@ static int xsk_generic_xmit(struct sock *sk) if (err == NETDEV_TX_BUSY) { /* Tell user-space to retry the send */ skb->destructor = sock_wfree; + spin_lock_irqsave(&xs->pool->cq_lock, flags); + xskq_prod_cancel(xs->pool->cq); + spin_unlock_irqrestore(&xs->pool->cq_lock, flags); /* Free skb without triggering the perf drop trace */ consume_skb(skb); err = -EAGAIN; diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h index 4a9663aa7afe6..2823b7c3302d0 100644 --- a/net/xdp/xsk_queue.h +++ b/net/xdp/xsk_queue.h @@ -334,6 +334,11 @@ static inline bool xskq_prod_is_full(struct xsk_queue *q) return xskq_prod_nb_free(q, 1) ? false : true; } +static inline void xskq_prod_cancel(struct xsk_queue *q) +{ + q->cached_prod--; +} + static inline int xskq_prod_reserve(struct xsk_queue *q) { if (xskq_prod_is_full(q)) -- 2.39.5