net/sock: Update memalloc_socks static key to modern api

No changes in refcount semantics -- key init is false; replace

static_key_slow_inc|dec   with   static_branch_inc|dec
static_key_false          with   static_branch_unlikely

Added a '_key' suffix to memalloc_socks, for better self
documentation.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sock.h

@@ -808,10 +808,10 @@ static inline bool sock_flag(const struct sock *sk, enum sock_flags flag)
 }
 
 #ifdef CONFIG_NET
-extern struct static_key memalloc_socks;
+DECLARE_STATIC_KEY_FALSE(memalloc_socks_key);
 static inline int sk_memalloc_socks(void)
 {
-	return static_key_false(&memalloc_socks);
+	return static_branch_unlikely(&memalloc_socks_key);
 }
 #else
 

net/core/sock.c

@@ -327,8 +327,8 @@ EXPORT_SYMBOL(sysctl_optmem_max);
 
 int sysctl_tstamp_allow_data __read_mostly = 1;
 
-struct static_key memalloc_socks = STATIC_KEY_INIT_FALSE;
-EXPORT_SYMBOL_GPL(memalloc_socks);
+DEFINE_STATIC_KEY_FALSE(memalloc_socks_key);
+EXPORT_SYMBOL_GPL(memalloc_socks_key);
 
 /**
  * sk_set_memalloc - sets %SOCK_MEMALLOC
@@ -342,7 +342,7 @@ void sk_set_memalloc(struct sock *sk)
 {
 	sock_set_flag(sk, SOCK_MEMALLOC);
 	sk->sk_allocation |= __GFP_MEMALLOC;
-	static_key_slow_inc(&memalloc_socks);
+	static_branch_inc(&memalloc_socks_key);
 }
 EXPORT_SYMBOL_GPL(sk_set_memalloc);
 
@@ -350,7 +350,7 @@ void sk_clear_memalloc(struct sock *sk)
 {
 	sock_reset_flag(sk, SOCK_MEMALLOC);
 	sk->sk_allocation &= ~__GFP_MEMALLOC;
-	static_key_slow_dec(&memalloc_socks);
+	static_branch_dec(&memalloc_socks_key);
 
 	/*
 	 * SOCK_MEMALLOC is allowed to ignore rmem limits to ensure forward