locking/spinlocks: Force inlining of spinlock ops

With both gcc 4.7.2 and 4.9.2, 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

In particular, with this config:

   http://busybox.net/~vda/kernel_config

there are more than a thousand copies of tiny spinlock-related
functions:

  $ nm --size-sort vmlinux | grep -iF ' t ' | uniq -c | grep -v '^ *1 ' | sort -rn | grep ' spin'
    473 000000000000000b t spin_unlock_irqrestore
    292 000000000000000b t spin_unlock
    215 000000000000000b t spin_lock
    134 000000000000000b t spin_unlock_irq
    130 000000000000000b t spin_unlock_bh
    120 000000000000000b t spin_lock_irq
    106 000000000000000b t spin_lock_bh

Disassembly:

 ffffffff81004720 <spin_lock>:
 ffffffff81004720:       55                      push   %rbp
 ffffffff81004721:       48 89 e5                mov    %rsp,%rbp
 ffffffff81004724:       e8 f8 4e e2 02          callq <_raw_spin_lock>
 ffffffff81004729:       5d                      pop    %rbp
 ffffffff8100472a:       c3                      retq

This patch fixes this via s/inline/__always_inline/ in
spinlock.h. This decreases vmlinux by about 40k:

      text     data      bss       dec     hex filename
  82375570 22255544 20627456 125258570 7774b4a vmlinux.before
  82335059 22255416 20627456 125217931 776ac8b vmlinux

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Thomas Graf <tgraf@suug.ch>
Link: http://lkml.kernel.org/r/1436812263-15243-1-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h
index 0063b24b4f36df594b3587daadfdaf8849192c7d..ffcd053ca89a9f22ea0f9842096fd5b0266a44c8 100644 (file)
--- a/include/linux/spinlock.h
+++ b/include/linux/spinlock.h
@@ -296,7 +296,7 @@ static inline void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock)
  * Map the spin_lock functions to the raw variants for PREEMPT_RT=n
  */
 
-static inline raw_spinlock_t *spinlock_check(spinlock_t *lock)
+static __always_inline raw_spinlock_t *spinlock_check(spinlock_t *lock)
 {
        return &lock->rlock;
 }
@@ -307,17 +307,17 @@ do {                                                      \
        raw_spin_lock_init(&(_lock)->rlock);            \
 } while (0)
 
-static inline void spin_lock(spinlock_t *lock)
+static __always_inline void spin_lock(spinlock_t *lock)
 {
        raw_spin_lock(&lock->rlock);
 }
 
-static inline void spin_lock_bh(spinlock_t *lock)
+static __always_inline void spin_lock_bh(spinlock_t *lock)
 {
        raw_spin_lock_bh(&lock->rlock);
 }
 
-static inline int spin_trylock(spinlock_t *lock)
+static __always_inline int spin_trylock(spinlock_t *lock)
 {
        return raw_spin_trylock(&lock->rlock);
 }
@@ -337,7 +337,7 @@ do {                                                                        \
        raw_spin_lock_nest_lock(spinlock_check(lock), nest_lock);       \
 } while (0)
 
-static inline void spin_lock_irq(spinlock_t *lock)
+static __always_inline void spin_lock_irq(spinlock_t *lock)
 {
        raw_spin_lock_irq(&lock->rlock);
 }
@@ -352,32 +352,32 @@ do {                                                                      \
        raw_spin_lock_irqsave_nested(spinlock_check(lock), flags, subclass); \
 } while (0)
 
-static inline void spin_unlock(spinlock_t *lock)
+static __always_inline void spin_unlock(spinlock_t *lock)
 {
        raw_spin_unlock(&lock->rlock);
 }
 
-static inline void spin_unlock_bh(spinlock_t *lock)
+static __always_inline void spin_unlock_bh(spinlock_t *lock)
 {
        raw_spin_unlock_bh(&lock->rlock);
 }
 
-static inline void spin_unlock_irq(spinlock_t *lock)
+static __always_inline void spin_unlock_irq(spinlock_t *lock)
 {
        raw_spin_unlock_irq(&lock->rlock);
 }
 
-static inline void spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags)
+static __always_inline void spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags)
 {
        raw_spin_unlock_irqrestore(&lock->rlock, flags);
 }
 
-static inline int spin_trylock_bh(spinlock_t *lock)
+static __always_inline int spin_trylock_bh(spinlock_t *lock)
 {
        return raw_spin_trylock_bh(&lock->rlock);
 }
 
-static inline int spin_trylock_irq(spinlock_t *lock)
+static __always_inline int spin_trylock_irq(spinlock_t *lock)
 {
        return raw_spin_trylock_irq(&lock->rlock);
 }
@@ -387,22 +387,22 @@ static inline int spin_trylock_irq(spinlock_t *lock)
        raw_spin_trylock_irqsave(spinlock_check(lock), flags); \
 })
 
-static inline void spin_unlock_wait(spinlock_t *lock)
+static __always_inline void spin_unlock_wait(spinlock_t *lock)
 {
        raw_spin_unlock_wait(&lock->rlock);
 }
 
-static inline int spin_is_locked(spinlock_t *lock)
+static __always_inline int spin_is_locked(spinlock_t *lock)
 {
        return raw_spin_is_locked(&lock->rlock);
 }
 
-static inline int spin_is_contended(spinlock_t *lock)
+static __always_inline int spin_is_contended(spinlock_t *lock)
 {
        return raw_spin_is_contended(&lock->rlock);
 }
 
-static inline int spin_can_lock(spinlock_t *lock)
+static __always_inline int spin_can_lock(spinlock_t *lock)
 {
        return raw_spin_can_lock(&lock->rlock);
 }