Update Linux to v5.10.109

Sourced from [1]

[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.10.109.tar.xz

Change-Id: I19bca9fc6762d4e63bcf3e4cba88bbe560d9c76c
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/include/net/neighbour.h b/include/net/neighbour.h
index 2be8d6b..d5767e2 100644
--- a/include/net/neighbour.h
+++ b/include/net/neighbour.h
@@ -174,7 +174,7 @@ struct pneigh_entry {
 	struct net_device	*dev;
 	u8			flags;
 	u8			protocol;
-	u8			key[0];
+	u8			key[];
 };
 
 /*
@@ -253,6 +253,7 @@ static inline void *neighbour_priv(const struct neighbour *n)
 #define NEIGH_UPDATE_F_OVERRIDE			0x00000001
 #define NEIGH_UPDATE_F_WEAK_OVERRIDE		0x00000002
 #define NEIGH_UPDATE_F_OVERRIDE_ISROUTER	0x00000004
+#define NEIGH_UPDATE_F_USE			0x10000000
 #define NEIGH_UPDATE_F_EXT_LEARNED		0x20000000
 #define NEIGH_UPDATE_F_ISROUTER			0x40000000
 #define NEIGH_UPDATE_F_ADMIN			0x80000000
@@ -393,13 +394,12 @@ void *neigh_seq_next(struct seq_file *, void *, loff_t *);
 void neigh_seq_stop(struct seq_file *, void *);
 
 int neigh_proc_dointvec(struct ctl_table *ctl, int write,
-			void __user *buffer, size_t *lenp, loff_t *ppos);
+			void *buffer, size_t *lenp, loff_t *ppos);
 int neigh_proc_dointvec_jiffies(struct ctl_table *ctl, int write,
-				void __user *buffer,
+				void *buffer,
 				size_t *lenp, loff_t *ppos);
 int neigh_proc_dointvec_ms_jiffies(struct ctl_table *ctl, int write,
-				   void __user *buffer,
-				   size_t *lenp, loff_t *ppos);
+				   void *buffer, size_t *lenp, loff_t *ppos);
 
 int neigh_sysctl_register(struct net_device *dev, struct neigh_parms *p,
 			  proc_handler *proc_handler);
@@ -505,10 +505,15 @@ static inline int neigh_output(struct neighbour *n, struct sk_buff *skb,
 {
 	const struct hh_cache *hh = &n->hh;
 
-	if ((n->nud_state & NUD_CONNECTED) && hh->hh_len && !skip_cache)
+	/* n->nud_state and hh->hh_len could be changed under us.
+	 * neigh_hh_output() is taking care of the race later.
+	 */
+	if (!skip_cache &&
+	    (READ_ONCE(n->nud_state) & NUD_CONNECTED) &&
+	    READ_ONCE(hh->hh_len))
 		return neigh_hh_output(hh, skb);
-	else
-		return n->output(n, skb);
+
+	return n->output(n, skb);
 }
 
 static inline struct neighbour *