net: force inlining of netif_tx_start/stop_queue, sock_hold, __sock_put

Sometimes gcc mysteriously doesn't inline very small functions we expect to be inlined. See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66122 Arguably, gcc should do better, but gcc people aren't willing to invest time into it, asking to use __always_inline instead. With this .config: http://busybox.net/~vda/kernel_config_OPTIMIZE_INLINING_and_Os, the following functions get deinlined many times. netif_tx_stop_queue: 207 copies, 590 calls: 55 push %rbp 48 89 e5 mov %rsp,%rbp f0 80 8f e0 01 00 00 01 lock orb $0x1,0x1e0(%rdi) 5d pop %rbp c3 retq netif_tx_start_queue: 47 copies, 111 calls 55 push %rbp 48 89 e5 mov %rsp,%rbp f0 80 a7 e0 01 00 00 fe lock andb $0xfe,0x1e0(%rdi) 5d pop %rbp c3 retq sock_hold: 39 copies, 124 calls 55 push %rbp 48 89 e5 mov %rsp,%rbp f0 ff 87 80 00 00 00 lock incl 0x80(%rdi) 5d pop %rbp c3 retq __sock_put: 6 copies, 13 calls 55 push %rbp 48 89 e5 mov %rsp,%rbp f0 ff 8f 80 00 00 00 lock decl 0x80(%rdi) 5d pop %rbp c3 retq This patch fixes this via s/inline/__always_inline/. Code size decrease after the patch is ~2.5k: text data bss dec hex filename 56719876 56364551 36196352 149280779 8e5d80b vmlinux_before 56717440 56364551 36196352 149278343 8e5ce87 vmlinux Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com> CC: David S. Miller <davem@davemloft.net> CC: linux-kernel@vger.kernel.org CC: netdev@vger.kernel.org CC: netfilter-devel@vger.kernel.org Signed-off-by: David S. Miller <davem@davemloft.net>
mariux64 · Apr 14, 2016 · f9a7cbb · f9a7cbb
1 parent bf91795
commit f9a7cbb
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Showing 2 changed files with 4 additions and 4 deletions.
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
@@ -2787,7 +2787,7 @@ static inline void netif_tx_schedule_all(struct net_device *dev)
 		netif_schedule_queue(netdev_get_tx_queue(dev, i));
 }
 
-static inline void netif_tx_start_queue(struct netdev_queue *dev_queue)
+static __always_inline void netif_tx_start_queue(struct netdev_queue *dev_queue)
 {
 	clear_bit(__QUEUE_STATE_DRV_XOFF, &dev_queue->state);
 }
@@ -2837,7 +2837,7 @@ static inline void netif_tx_wake_all_queues(struct net_device *dev)
 	}
 }
 
-static inline void netif_tx_stop_queue(struct netdev_queue *dev_queue)
+static __always_inline void netif_tx_stop_queue(struct netdev_queue *dev_queue)
 {
 	set_bit(__QUEUE_STATE_DRV_XOFF, &dev_queue->state);
 }

diff --git a/include/net/sock.h b/include/net/sock.h
@@ -569,15 +569,15 @@ static inline bool __sk_del_node_init(struct sock *sk)
    modifications.
  */
 
-static inline void sock_hold(struct sock *sk)
+static __always_inline void sock_hold(struct sock *sk)
 {
 	atomic_inc(&sk->sk_refcnt);
 }
 
 /* Ungrab socket in the context, which assumes that socket refcnt
    cannot hit zero, f.e. it is true in context of any socketcall.
  */
-static inline void __sock_put(struct sock *sk)
+static __always_inline void __sock_put(struct sock *sk)
 {
 	atomic_dec(&sk->sk_refcnt);
 }