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Commit a79f0da8 authored by Eric Dumazet's avatar Eric Dumazet Committed by Ingo Molnar
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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: default avatarEric 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: default avatarIngo Molnar <mingo@elte.hu>
parent ddf9a003

arch/x86/include/asm/atomic_32.h

+22 −0
Original line number Diff line number Diff line
@@ -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);



/**

arch/x86/lib/atomic64_32.c

+1 −22
Original line number Diff line number Diff line
@@ -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