From 7c8f348390652a67e9356eec9cd2b0f76a9c7c72 Mon Sep 17 00:00:00 2001 From: Martin Lucina Date: Thu, 4 Dec 2014 14:33:53 +0100 Subject: [PATCH] Mini-OS: netfront: Fix rx ring starvation in network_rx In network_rx() we must push the same amount of requests back onto the ring in the second loop that we consumed in the first loop. Otherwise the ring will eventually starve itself of free request slots and no packets will be delivered. Further, we make the HAVE_LIBC codepath clearer to follow by removing the "some" variable from the for loop initialisation and conditions. Signed-off-by: Martin Lucina Acked-by: Samuel Thibault --- netfront.c | 36 +++++++++++++++++------------------- 1 file changed, 17 insertions(+), 19 deletions(-) diff --git a/netfront.c b/netfront.c index 44c3995..42bb103 100644 --- a/netfront.c +++ b/netfront.c @@ -96,42 +96,35 @@ static inline int xennet_rxidx(RING_IDX idx) void network_rx(struct netfront_dev *dev) { RING_IDX rp,cons,req_prod; - struct netif_rx_response *rx; - int nr_consumed, some, more, i, notify; - + int nr_consumed, more, i, notify; +#ifdef HAVE_LIBC + int some; +#endif + nr_consumed = 0; moretodo: rp = dev->rx.sring->rsp_prod; rmb(); /* Ensure we see queued responses up to 'rp'. */ - cons = dev->rx.rsp_cons; - for (nr_consumed = 0, some = 0; - (cons != rp) && !some; - nr_consumed++, cons++) +#ifdef HAVE_LIBC + some = 0; +#endif + for (cons = dev->rx.rsp_cons; cons != rp; nr_consumed++, cons++) { struct net_buffer* buf; unsigned char* page; int id; - rx = RING_GET_RESPONSE(&dev->rx, cons); - - if (rx->flags & NETRXF_extra_info) - { - printk("+++++++++++++++++++++ we have extras!\n"); - continue; - } - - - if (rx->status == NETIF_RSP_NULL) continue; + struct netif_rx_response *rx = RING_GET_RESPONSE(&dev->rx, cons); id = rx->id; - BUG_ON(id >= NET_TX_RING_SIZE); + BUG_ON(id >= NET_RX_RING_SIZE); buf = &dev->rx_buffers[id]; page = (unsigned char*)buf->page; gnttab_end_access(buf->gref); - if(rx->status>0) + if (rx->status > NETIF_RSP_NULL) { #ifdef HAVE_LIBC if (dev->netif_rx == NETIF_SELECT_RX) { @@ -142,6 +135,7 @@ moretodo: memcpy(dev->data, page+rx->offset, len); dev->rlen = len; some = 1; + break; } else #endif dev->netif_rx(page+rx->offset,rx->status); @@ -150,7 +144,11 @@ moretodo: dev->rx.rsp_cons=cons; RING_FINAL_CHECK_FOR_RESPONSES(&dev->rx,more); +#ifdef HAVE_LIBC if(more && !some) goto moretodo; +#else + if(more) goto moretodo; +#endif req_prod = dev->rx.req_prod_pvt; -- 2.39.5