Hi, all. I have found recently the Linux kernel will complain occasionally
a dead lock, while I use the kernel module rte_kni provided in DPDK. After
reviewing the dpdk source code and googling,
I found that the deadlock occurred because netif_receive_skb is invoked in
a non-softirq context. The erroneous source code is listed as below (in
lib/librte_eal/linuxapp/kni/kni_net.c:kni_net_rx_normal):
* /* Transfer received packets to netif */
for (i = 0; i < num; i++) {
kva = (void *)va[i] - kni->mbuf_va + kni->mbuf_kva;
len = kva->data_len;
data_kva = kva->data - kni->mbuf_va + kni->mbuf_kva;
skb = dev_alloc_skb(len + 2);
if (!skb) {
KNI_ERR("Out of mem, dropping pkts\n");
/* Update statistics */
kni->stats.rx_dropped++;
}
else {
/* Align IP on 16B boundary */
skb_reserve(skb, 2);
memcpy(skb_put(skb, len), data_kva, len);
skb->dev = dev;
skb->protocol = eth_type_trans(skb, dev);
skb->ip_summed = CHECKSUM_UNNECESSARY;
/* Call netif interface */
netif_receive_skb(skb);
/* Update statistics */
kni->stats.rx_bytes += len;
kni->stats.rx_packets++;
}
}*
The similar bug is reported and fixed in dpdk extension memnic. See
http://comments.gmane.org/gmane.comp.networking.dpdk.devel/3151
To fix this bug, we should call local_bh_disable/local_bh_enable
around netif_receive_skb to disable and re-enable soft-irq.
Best Regards
