diff options
| author | Eric Dumazet | 2009-07-03 16:50:10 +0200 |
|---|---|---|
| committer | Ingo Molnar | 2009-07-04 11:45:00 +0200 |
| commit | a79f0da80a508448434476b77f9d3d1a469eab67 (patch) | |
| tree | 1bf9c72a09d266d874a2e8f7c94fd81e8ad27feb | |
| parent | ddf9a003d32f720805ac30bcc15755e9289073de (diff) | |
x86: atomic64: Inline atomic64_read() again
Now atomic64_read() is light weight (no register pressure and
small icache), we can inline it again.
Also use "=&A" constraint instead of "+A" to avoid warning
about unitialized 'res' variable. (gcc had to force 0 in eax/edx)
$ size vmlinux.prev vmlinux.after
text data bss dec hex filename
4908667 451676 1684868 7045211 6b805b vmlinux.prev
4908651 451676 1684868 7045195 6b804b vmlinux.after
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
LKML-Reference: <4A4E1AA2.30002@gmail.com>
[ Also fix typo in atomic64_set() export ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
| -rw-r--r-- | arch/x86/include/asm/atomic_32.h | 22 | ||||
| -rw-r--r-- | arch/x86/lib/atomic64_32.c | 23 |
2 files changed, 23 insertions, 22 deletions
diff --git a/arch/x86/include/asm/atomic_32.h b/arch/x86/include/asm/atomic_32.h index d7c8849b8c67..dc5a667ff791 100644 --- a/arch/x86/include/asm/atomic_32.h +++ b/arch/x86/include/asm/atomic_32.h @@ -295,6 +295,28 @@ extern void atomic64_set(atomic64_t *ptr, u64 new_val); * * Atomically reads the value of @ptr and returns it. */ +static inline u64 atomic64_read(atomic64_t *ptr) +{ + u64 res; + + /* + * Note, we inline this atomic64_t primitive because + * it only clobbers EAX/EDX and leaves the others + * untouched. We also (somewhat subtly) rely on the + * fact that cmpxchg8b returns the current 64-bit value + * of the memory location we are touching: + */ + asm volatile( + "mov %%ebx, %%eax\n\t" + "mov %%ecx, %%edx\n\t" + LOCK_PREFIX "cmpxchg8b %1\n" + : "=&A" (res) + : "m" (*ptr) + ); + + return res; +} + extern u64 atomic64_read(atomic64_t *ptr); /** diff --git a/arch/x86/lib/atomic64_32.c b/arch/x86/lib/atomic64_32.c index 1d98c9eb6eac..824fa0be55a3 100644 --- a/arch/x86/lib/atomic64_32.c +++ b/arch/x86/lib/atomic64_32.c @@ -66,31 +66,10 @@ void atomic64_set(atomic64_t *ptr, u64 new_val) { atomic64_xchg(ptr, new_val); } -EXPORT_SYMBOL(atomic64_read); +EXPORT_SYMBOL(atomic64_set); /** - * atomic64_read - read atomic64 variable - * @ptr: pointer to type atomic64_t - * - * Atomically reads the value of @ptr and returns it. - */ -u64 atomic64_read(atomic64_t *ptr) -{ - u64 res; - - asm volatile( - "mov %%ebx, %%eax\n\t" - "mov %%ecx, %%edx\n\t" - LOCK_PREFIX "cmpxchg8b %1\n" - : "+A" (res) - : "m" (*ptr) - ); - - return res; -} EXPORT_SYMBOL(atomic64_read); - -/** * atomic64_add_return - add and return * @delta: integer value to add * @ptr: pointer to type atomic64_t |