Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

1 files changed, 436 insertions, 0 deletions

diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
new file mode 100644
index 000000000..b9e8d2b75
--- /dev/null
+++ b/include/net/ip6_route.h
@@ -0,0 +1,436 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _NET_IP6_ROUTE_H
+#define _NET_IP6_ROUTE_H
+
+#include <net/addrconf.h>
+#include <net/flow.h>
+#include <net/ip6_fib.h>
+#include <net/sock.h>
+#include <net/lwtunnel.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <linux/route.h>
+#include <net/nexthop.h>
+
+struct route_info {
+	__u8			type;
+	__u8			length;
+	__u8			prefix_len;
+#if defined(__BIG_ENDIAN_BITFIELD)
+	__u8			reserved_h:3,
+				route_pref:2,
+				reserved_l:3;
+#elif defined(__LITTLE_ENDIAN_BITFIELD)
+	__u8			reserved_l:3,
+				route_pref:2,
+				reserved_h:3;
+#endif
+	__be32			lifetime;
+	__u8			prefix[];	/* 0,8 or 16 */
+};
+
+#define RT6_LOOKUP_F_IFACE		0x00000001
+#define RT6_LOOKUP_F_REACHABLE		0x00000002
+#define RT6_LOOKUP_F_HAS_SADDR		0x00000004
+#define RT6_LOOKUP_F_SRCPREF_TMP	0x00000008
+#define RT6_LOOKUP_F_SRCPREF_PUBLIC	0x00000010
+#define RT6_LOOKUP_F_SRCPREF_COA	0x00000020
+#define RT6_LOOKUP_F_IGNORE_LINKSTATE	0x00000040
+#define RT6_LOOKUP_F_DST_NOREF		0x00000080
+
+/* We do not (yet ?) support IPv6 jumbograms (RFC 2675)
+ * Unlike IPv4, hdr->seg_len doesn't include the IPv6 header
+ */
+#define IP6_MAX_MTU (0xFFFF + sizeof(struct ipv6hdr))
+
+/*
+ * rt6_srcprefs2flags() and rt6_flags2srcprefs() translate
+ * between IPV6_ADDR_PREFERENCES socket option values
+ *	IPV6_PREFER_SRC_TMP    = 0x1
+ *	IPV6_PREFER_SRC_PUBLIC = 0x2
+ *	IPV6_PREFER_SRC_COA    = 0x4
+ * and above RT6_LOOKUP_F_SRCPREF_xxx flags.
+ */
+static inline int rt6_srcprefs2flags(unsigned int srcprefs)
+{
+	return (srcprefs & IPV6_PREFER_SRC_MASK) << 3;
+}
+
+static inline unsigned int rt6_flags2srcprefs(int flags)
+{
+	return (flags >> 3) & IPV6_PREFER_SRC_MASK;
+}
+
+static inline bool rt6_need_strict(const struct in6_addr *daddr)
+{
+	return ipv6_addr_type(daddr) &
+		(IPV6_ADDR_MULTICAST | IPV6_ADDR_LINKLOCAL | IPV6_ADDR_LOOPBACK);
+}
+
+/* fib entries using a nexthop object can not be coalesced into
+ * a multipath route
+ */
+static inline bool rt6_qualify_for_ecmp(const struct fib6_info *f6i)
+{
+	/* the RTF_ADDRCONF flag filters out RA's */
+	return !(f6i->fib6_flags & RTF_ADDRCONF) && !f6i->nh &&
+		f6i->fib6_nh->fib_nh_gw_family;
+}
+
+#if IS_ENABLED(CONFIG_IPV6)
+void ip6_route_input(struct sk_buff *skb);
+#else
+static inline void ip6_route_input(struct sk_buff *skb)
+{
+}
+#endif
+
+struct dst_entry *ip6_route_input_lookup(struct net *net,
+					 struct net_device *dev,
+					 struct flowi6 *fl6,
+					 const struct sk_buff *skb, int flags);
+
+struct dst_entry *ip6_route_output_flags(struct net *net, const struct sock *sk,
+					 struct flowi6 *fl6, int flags);
+
+static inline struct dst_entry *ip6_route_output(struct net *net,
+						 const struct sock *sk,
+						 struct flowi6 *fl6)
+{
+	return ip6_route_output_flags(net, sk, fl6, 0);
+}
+
+/* Only conditionally release dst if flags indicates
+ * !RT6_LOOKUP_F_DST_NOREF or dst is in uncached_list.
+ */
+static inline void ip6_rt_put_flags(struct rt6_info *rt, int flags)
+{
+	if (!(flags & RT6_LOOKUP_F_DST_NOREF) ||
+	    !list_empty(&rt->dst.rt_uncached))
+		ip6_rt_put(rt);
+}
+
+struct dst_entry *ip6_route_lookup(struct net *net, struct flowi6 *fl6,
+				   const struct sk_buff *skb, int flags);
+struct rt6_info *ip6_pol_route(struct net *net, struct fib6_table *table,
+			       int ifindex, struct flowi6 *fl6,
+			       const struct sk_buff *skb, int flags);
+
+void ip6_route_init_special_entries(void);
+int ip6_route_init(void);
+void ip6_route_cleanup(void);
+
+int ipv6_route_ioctl(struct net *net, unsigned int cmd,
+		struct in6_rtmsg *rtmsg);
+
+int ip6_route_add(struct fib6_config *cfg, gfp_t gfp_flags,
+		  struct netlink_ext_ack *extack);
+int ip6_ins_rt(struct net *net, struct fib6_info *f6i);
+int ip6_del_rt_reason(struct net *net, struct fib6_info *f6i,
+		      enum rt_del_reason del_reason);
+#if IS_ENABLED(CONFIG_IPV6)
+int ip6_del_rt(struct net *net, struct fib6_info *f6i, bool skip_notify);
+#else
+static inline int ip6_del_rt(struct net *net, struct fib6_info *f6i,
+			     bool skip_notify)
+{
+	return -EAFNOSUPPORT;
+}
+#endif
+
+void rt6_flush_exceptions(struct fib6_info *f6i);
+void rt6_age_exceptions(struct fib6_info *f6i, struct fib6_gc_args *gc_args,
+			unsigned long now);
+
+static inline int ip6_route_get_saddr(struct net *net, struct fib6_info *f6i,
+				      const struct in6_addr *daddr,
+				      unsigned int prefs, int l3mdev_index,
+				      struct in6_addr *saddr)
+{
+	struct net_device *l3mdev;
+	struct net_device *dev;
+	bool same_vrf;
+	int err = 0;
+
+	rcu_read_lock();
+
+	l3mdev = dev_get_by_index_rcu(net, l3mdev_index);
+	if (!f6i || !f6i->fib6_prefsrc.plen || l3mdev)
+		dev = f6i ? fib6_info_nh_dev(f6i) : NULL;
+	same_vrf = !l3mdev || l3mdev_master_dev_rcu(dev) == l3mdev;
+	if (f6i && f6i->fib6_prefsrc.plen && same_vrf)
+		*saddr = f6i->fib6_prefsrc.addr;
+	else
+		err = ipv6_dev_get_saddr(net, same_vrf ? dev : l3mdev, daddr, prefs, saddr);
+
+	rcu_read_unlock();
+
+	return err;
+}
+
+struct rt6_info *rt6_lookup(struct net *net, const struct in6_addr *daddr,
+			    const struct in6_addr *saddr, int oif,
+			    const struct sk_buff *skb, int flags);
+u32 rt6_multipath_hash(const struct net *net, const struct flowi6 *fl6,
+		       const struct sk_buff *skb, struct flow_keys *hkeys);
+
+struct dst_entry *icmp6_dst_alloc(struct net_device *dev, struct flowi6 *fl6);
+
+void fib6_force_start_gc(struct net *net);
+
+struct fib6_info *addrconf_f6i_alloc(struct net *net, struct inet6_dev *idev,
+				     const struct in6_addr *addr, bool anycast,
+				     gfp_t gfp_flags, struct netlink_ext_ack *extack);
+
+struct rt6_info *ip6_dst_alloc(struct net *net, struct net_device *dev,
+			       int flags);
+
+/*
+ *	support functions for ND
+ *
+ */
+struct fib6_info *rt6_get_dflt_router(struct net *net,
+				     const struct in6_addr *addr,
+				     struct net_device *dev);
+struct fib6_info *rt6_add_dflt_router(struct net *net,
+				     const struct in6_addr *gwaddr,
+				     struct net_device *dev, unsigned int pref,
+				     u32 defrtr_usr_metric,
+				     int lifetime);
+
+void rt6_purge_dflt_routers(struct net *net);
+
+int rt6_route_rcv(struct net_device *dev, u8 *opt, int len,
+		  const struct in6_addr *gwaddr);
+
+void ip6_update_pmtu(struct sk_buff *skb, struct net *net, __be32 mtu, int oif,
+		     u32 mark, kuid_t uid);
+void ip6_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, __be32 mtu);
+void ip6_redirect(struct sk_buff *skb, struct net *net, int oif, u32 mark,
+		  kuid_t uid);
+void ip6_redirect_no_header(struct sk_buff *skb, struct net *net, int oif);
+void ip6_sk_redirect(struct sk_buff *skb, struct sock *sk);
+
+struct netlink_callback;
+
+struct rt6_rtnl_dump_arg {
+	struct sk_buff *skb;
+	struct netlink_callback *cb;
+	struct net *net;
+	struct fib_dump_filter filter;
+};
+
+int rt6_dump_route(struct fib6_info *f6i, void *p_arg, unsigned int skip);
+void rt6_mtu_change(struct net_device *dev, unsigned int mtu);
+void rt6_remove_prefsrc(struct inet6_ifaddr *ifp);
+void rt6_clean_tohost(struct net *net, struct in6_addr *gateway);
+void rt6_sync_up(struct net_device *dev, unsigned char nh_flags);
+void rt6_disable_ip(struct net_device *dev, unsigned long event);
+void rt6_sync_down_dev(struct net_device *dev, unsigned long event);
+void rt6_multipath_rebalance(struct fib6_info *f6i);
+
+void rt6_uncached_list_add(struct rt6_info *rt);
+void rt6_uncached_list_del(struct rt6_info *rt);
+
+static inline const struct rt6_info *skb_rt6_info(const struct sk_buff *skb)
+{
+	const struct dst_entry *dst = skb_dst(skb);
+
+	if (dst)
+		return dst_rt6_info(dst);
+
+	return NULL;
+}
+
+/*
+ *	Store a destination cache entry in a socket
+ */
+static inline void ip6_dst_store(struct sock *sk, struct dst_entry *dst,
+				 bool daddr_set,
+				 bool saddr_set)
+{
+	struct ipv6_pinfo *np = inet6_sk(sk);
+
+	np->dst_cookie = rt6_get_cookie(dst_rt6_info(dst));
+	sk_setup_caps(sk, dst);
+	np->daddr_cache = daddr_set;
+#ifdef CONFIG_IPV6_SUBTREES
+	np->saddr_cache = saddr_set;
+#endif
+}
+
+void ip6_sk_dst_store_flow(struct sock *sk, struct dst_entry *dst,
+			   const struct flowi6 *fl6);
+
+static inline bool ipv6_unicast_destination(const struct sk_buff *skb)
+{
+	const struct rt6_info *rt = dst_rt6_info(skb_dst(skb));
+
+	return rt->rt6i_flags & RTF_LOCAL;
+}
+
+static inline bool __ipv6_anycast_destination(const struct rt6key *rt6i_dst,
+					      u32 rt6i_flags,
+					      const struct in6_addr *daddr)
+{
+	return rt6i_flags & RTF_ANYCAST ||
+	       (rt6i_dst->plen < 127 &&
+	       !(rt6i_flags & (RTF_GATEWAY | RTF_NONEXTHOP)) &&
+	       ipv6_addr_equal(&rt6i_dst->addr, daddr));
+}
+
+static inline bool ipv6_anycast_destination(const struct dst_entry *dst,
+					    const struct in6_addr *daddr)
+{
+	const struct rt6_info *rt = dst_rt6_info(dst);
+
+	return __ipv6_anycast_destination(&rt->rt6i_dst, rt->rt6i_flags, daddr);
+}
+
+#if IS_ENABLED(CONFIG_IPV6)
+int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
+		 int (*output)(struct net *, struct sock *, struct sk_buff *));
+#else
+static inline int ip6_fragment(struct net *net, struct sock *sk,
+			       struct sk_buff *skb,
+			       int (*output)(struct net *, struct sock *,
+					     struct sk_buff *))
+{
+	kfree_skb(skb);
+	return -EAFNOSUPPORT;
+}
+#endif
+
+/* Variant of dst_mtu() for IPv6 users */
+static inline u32 dst6_mtu(const struct dst_entry *dst)
+{
+	return INDIRECT_CALL_1(dst->ops->mtu, ip6_mtu, dst);
+}
+
+static inline unsigned int ip6_skb_dst_mtu(const struct sk_buff *skb)
+{
+	const struct ipv6_pinfo *np = skb->sk && !dev_recursion_level() ?
+				inet6_sk(skb->sk) : NULL;
+	const struct dst_entry *dst = skb_dst(skb);
+	unsigned int mtu;
+
+	if (np && READ_ONCE(np->pmtudisc) >= IPV6_PMTUDISC_PROBE) {
+		mtu = READ_ONCE(dst_dev(dst)->mtu);
+		mtu -= lwtunnel_headroom(dst->lwtstate, mtu);
+	} else {
+		mtu = dst_mtu(dst);
+	}
+	return mtu;
+}
+
+static inline bool ip6_sk_accept_pmtu(const struct sock *sk)
+{
+	u8 pmtudisc = READ_ONCE(inet6_sk(sk)->pmtudisc);
+
+	return pmtudisc != IPV6_PMTUDISC_INTERFACE &&
+	       pmtudisc != IPV6_PMTUDISC_OMIT;
+}
+
+static inline bool ip6_sk_ignore_df(const struct sock *sk)
+{
+	u8 pmtudisc = READ_ONCE(inet6_sk(sk)->pmtudisc);
+
+	return pmtudisc < IPV6_PMTUDISC_DO ||
+	       pmtudisc == IPV6_PMTUDISC_OMIT;
+}
+
+static inline const struct in6_addr *rt6_nexthop(const struct rt6_info *rt,
+						 const struct in6_addr *daddr)
+{
+	if (rt->rt6i_flags & RTF_GATEWAY)
+		return &rt->rt6i_gateway;
+	else if (unlikely(rt->rt6i_flags & RTF_CACHE))
+		return &rt->rt6i_dst.addr;
+	else
+		return daddr;
+}
+
+static inline bool rt6_duplicate_nexthop(struct fib6_info *a, struct fib6_info *b)
+{
+	struct fib6_nh *nha, *nhb;
+
+	if (a->nh || b->nh)
+		return nexthop_cmp(a->nh, b->nh);
+
+	nha = a->fib6_nh;
+	nhb = b->fib6_nh;
+	return nha->fib_nh_dev == nhb->fib_nh_dev &&
+	       ipv6_addr_equal(&nha->fib_nh_gw6, &nhb->fib_nh_gw6) &&
+	       !lwtunnel_cmp_encap(nha->fib_nh_lws, nhb->fib_nh_lws);
+}
+
+static inline unsigned int ip6_dst_mtu_maybe_forward(const struct dst_entry *dst,
+						     bool forwarding)
+{
+	struct inet6_dev *idev;
+	unsigned int mtu;
+
+	if (!forwarding || dst_metric_locked(dst, RTAX_MTU)) {
+		mtu = dst_metric_raw(dst, RTAX_MTU);
+		if (mtu)
+			goto out;
+	}
+
+	mtu = IPV6_MIN_MTU;
+	rcu_read_lock();
+	idev = __in6_dev_get(dst_dev_rcu(dst));
+	if (idev)
+		mtu = READ_ONCE(idev->cnf.mtu6);
+	rcu_read_unlock();
+
+out:
+	mtu = min_t(unsigned int, mtu, IP6_MAX_MTU);
+
+	return mtu - lwtunnel_headroom(dst->lwtstate, mtu);
+}
+
+/* Configured/administrative MTU of a route, for advertising the TCP MSS.
+ *
+ * Unlike ip6_dst_mtu_maybe_forward(), this ignores any ICMPv6-learned path
+ * MTU (which is kept on the RTF_CACHE exception route) and returns the MTU of
+ * the underlying route (fib6_pmtu) or the egress device.  The advertised MSS
+ * bounds what the peer may send to us and must reflect our receive
+ * capability, not a path MTU learned on the reverse (send) direction.  See
+ * RFC 2923 section 2.3 and the comment above tcp_advertise_mss().
+ */
+static inline unsigned int ip6_dst_mtu_configured(const struct dst_entry *dst)
+{
+	const struct rt6_info *rt = dst_rt6_info(dst);
+	const struct fib6_info *from;
+	struct inet6_dev *idev;
+	unsigned int mtu = 0;
+
+	rcu_read_lock();
+	/* IPv6 keeps the learned PMTU and the configured MTU in the same
+	 * RTAX_MTU slot: the learned value sits on this (possibly RTF_CACHE)
+	 * dst, the configured one on the underlying route.  Reach the latter
+	 * via ->from (fib6_pmtu), populated by ip6_route_info_create().
+	 */
+	from = rcu_dereference(rt->from);
+	if (from)
+		mtu = from->fib6_pmtu;
+	if (!mtu) {
+		mtu = IPV6_MIN_MTU;
+		idev = __in6_dev_get(dst_dev_rcu(dst));
+		if (idev)
+			mtu = max_t(unsigned int, mtu, READ_ONCE(idev->cnf.mtu6));
+	}
+	rcu_read_unlock();
+
+	mtu = min_t(unsigned int, mtu, IP6_MAX_MTU);
+	return mtu - lwtunnel_headroom(dst->lwtstate, mtu);
+}
+
+u32 ip6_mtu_from_fib6(const struct fib6_result *res,
+		      const struct in6_addr *daddr,
+		      const struct in6_addr *saddr);
+
+struct neighbour *ip6_neigh_lookup(const struct in6_addr *gw,
+				   struct net_device *dev, struct sk_buff *skb,
+				   const void *daddr);
+#endif