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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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b4fe85f9c9
Drivers like vxlan use the recently introduced udp_tunnel_xmit_skb/udp_tunnel6_xmit_skb APIs. udp_tunnel6_xmit_skb makes use of ip6tunnel_xmit, and ip6tunnel_xmit, after sending the packet, updates the struct stats using the usual u64_stats_update_begin/end calls on this_cpu_ptr(dev->tstats). udp_tunnel_xmit_skb makes use of iptunnel_xmit, which doesn't touch tstats, so drivers like vxlan, immediately after, call iptunnel_xmit_stats, which does the same thing - calls u64_stats_update_begin/end on this_cpu_ptr(dev->tstats). While vxlan is probably fine (I don't know?), calling a similar function from, say, an unbound workqueue, on a fully preemptable kernel causes real issues: [ 188.434537] BUG: using smp_processor_id() in preemptible [00000000] code: kworker/u8:0/6 [ 188.435579] caller is debug_smp_processor_id+0x17/0x20 [ 188.435583] CPU: 0 PID: 6 Comm: kworker/u8:0 Not tainted 4.2.6 #2 [ 188.435607] Call Trace: [ 188.435611] [<ffffffff8234e936>] dump_stack+0x4f/0x7b [ 188.435615] [<ffffffff81915f3d>] check_preemption_disabled+0x19d/0x1c0 [ 188.435619] [<ffffffff81915f77>] debug_smp_processor_id+0x17/0x20 The solution would be to protect the whole this_cpu_ptr(dev->tstats)/u64_stats_update_begin/end blocks with disabling preemption and then reenabling it. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
105 lines
3.2 KiB
C
105 lines
3.2 KiB
C
#ifndef _NET_IP6_TUNNEL_H
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#define _NET_IP6_TUNNEL_H
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#include <linux/ipv6.h>
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#include <linux/netdevice.h>
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#include <linux/if_tunnel.h>
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#include <linux/ip6_tunnel.h>
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#define IP6TUNNEL_ERR_TIMEO (30*HZ)
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/* capable of sending packets */
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#define IP6_TNL_F_CAP_XMIT 0x10000
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/* capable of receiving packets */
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#define IP6_TNL_F_CAP_RCV 0x20000
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/* determine capability on a per-packet basis */
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#define IP6_TNL_F_CAP_PER_PACKET 0x40000
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struct __ip6_tnl_parm {
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char name[IFNAMSIZ]; /* name of tunnel device */
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int link; /* ifindex of underlying L2 interface */
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__u8 proto; /* tunnel protocol */
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__u8 encap_limit; /* encapsulation limit for tunnel */
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__u8 hop_limit; /* hop limit for tunnel */
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__be32 flowinfo; /* traffic class and flowlabel for tunnel */
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__u32 flags; /* tunnel flags */
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struct in6_addr laddr; /* local tunnel end-point address */
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struct in6_addr raddr; /* remote tunnel end-point address */
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__be16 i_flags;
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__be16 o_flags;
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__be32 i_key;
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__be32 o_key;
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};
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struct ip6_tnl_dst {
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seqlock_t lock;
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struct dst_entry __rcu *dst;
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u32 cookie;
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};
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/* IPv6 tunnel */
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struct ip6_tnl {
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struct ip6_tnl __rcu *next; /* next tunnel in list */
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struct net_device *dev; /* virtual device associated with tunnel */
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struct net *net; /* netns for packet i/o */
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struct __ip6_tnl_parm parms; /* tunnel configuration parameters */
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struct flowi fl; /* flowi template for xmit */
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struct ip6_tnl_dst __percpu *dst_cache; /* cached dst */
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int err_count;
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unsigned long err_time;
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/* These fields used only by GRE */
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__u32 i_seqno; /* The last seen seqno */
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__u32 o_seqno; /* The last output seqno */
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int hlen; /* Precalculated GRE header length */
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int mlink;
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};
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/* Tunnel encapsulation limit destination sub-option */
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struct ipv6_tlv_tnl_enc_lim {
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__u8 type; /* type-code for option */
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__u8 length; /* option length */
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__u8 encap_limit; /* tunnel encapsulation limit */
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} __packed;
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struct dst_entry *ip6_tnl_dst_get(struct ip6_tnl *t);
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int ip6_tnl_dst_init(struct ip6_tnl *t);
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void ip6_tnl_dst_destroy(struct ip6_tnl *t);
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void ip6_tnl_dst_reset(struct ip6_tnl *t);
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void ip6_tnl_dst_set(struct ip6_tnl *t, struct dst_entry *dst);
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int ip6_tnl_rcv_ctl(struct ip6_tnl *t, const struct in6_addr *laddr,
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const struct in6_addr *raddr);
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int ip6_tnl_xmit_ctl(struct ip6_tnl *t, const struct in6_addr *laddr,
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const struct in6_addr *raddr);
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__u16 ip6_tnl_parse_tlv_enc_lim(struct sk_buff *skb, __u8 *raw);
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__u32 ip6_tnl_get_cap(struct ip6_tnl *t, const struct in6_addr *laddr,
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const struct in6_addr *raddr);
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struct net *ip6_tnl_get_link_net(const struct net_device *dev);
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int ip6_tnl_get_iflink(const struct net_device *dev);
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static inline void ip6tunnel_xmit(struct sock *sk, struct sk_buff *skb,
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struct net_device *dev)
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{
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struct net_device_stats *stats = &dev->stats;
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int pkt_len, err;
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pkt_len = skb->len - skb_inner_network_offset(skb);
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err = ip6_local_out(dev_net(skb_dst(skb)->dev), sk, skb);
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if (net_xmit_eval(err) == 0) {
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struct pcpu_sw_netstats *tstats = get_cpu_ptr(dev->tstats);
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u64_stats_update_begin(&tstats->syncp);
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tstats->tx_bytes += pkt_len;
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tstats->tx_packets++;
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u64_stats_update_end(&tstats->syncp);
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put_cpu_ptr(tstats);
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} else {
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stats->tx_errors++;
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stats->tx_aborted_errors++;
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}
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}
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#endif
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