mirror of
https://github.com/FEX-Emu/linux.git
synced 2024-12-18 06:50:08 +00:00
129f69465b
* EXPORT_SYMBOL's moved to other files * #include <linux/config.h>, <linux/module.h> where needed * #include's in i386_ksyms.c cleaned up * After copy-paste, redundant due to Makefiles rules preprocessor directives removed: #ifdef CONFIG_FOO EXPORT_SYMBOL(foo); #endif obj-$(CONFIG_FOO) += foo.o * Tiny reformat to fit in 80 columns Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
43 lines
842 B
C
43 lines
842 B
C
/*
|
|
* x86 version of "atomic_dec_and_lock()" using
|
|
* the atomic "cmpxchg" instruction.
|
|
*
|
|
* (For CPU's lacking cmpxchg, we use the slow
|
|
* generic version, and this one never even gets
|
|
* compiled).
|
|
*/
|
|
|
|
#include <linux/spinlock.h>
|
|
#include <linux/module.h>
|
|
#include <asm/atomic.h>
|
|
|
|
int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock)
|
|
{
|
|
int counter;
|
|
int newcount;
|
|
|
|
repeat:
|
|
counter = atomic_read(atomic);
|
|
newcount = counter-1;
|
|
|
|
if (!newcount)
|
|
goto slow_path;
|
|
|
|
asm volatile("lock; cmpxchgl %1,%2"
|
|
:"=a" (newcount)
|
|
:"r" (newcount), "m" (atomic->counter), "0" (counter));
|
|
|
|
/* If the above failed, "eax" will have changed */
|
|
if (newcount != counter)
|
|
goto repeat;
|
|
return 0;
|
|
|
|
slow_path:
|
|
spin_lock(lock);
|
|
if (atomic_dec_and_test(atomic))
|
|
return 1;
|
|
spin_unlock(lock);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(_atomic_dec_and_lock);
|