lib: fix atomic64_cmpxchg issue on 32bits environment

thehajime · thehajime · commit 71a2ed7d393d · 2015-05-11T15:31:48.000+02:00
it caused the undefined symbol of wrong_size_cmpxchg() during a runtime.

Signed-off-by: Hajime Tazaki &lt;tazaki@sfc.wide.ad.jp&gt;
diff --git a/arch/lib/include/asm/atomic.h b/arch/lib/include/asm/atomic.h
@@ -42,7 +42,12 @@ long atomic64_sub_return(long i, atomic64_t *v);
 #define atomic64_dec_return(v)  (atomic64_sub_return(1, (v)))
 static inline long atomic64_cmpxchg(atomic64_t *v, long old, long new)
 {
-	return cmpxchg(&v->counter, old, new);
+	long long val;
+
+	val = v->counter;
+	if (val == old)
+		v->counter = new;
+	return val;
 }
 long atomic64_xchg(atomic64_t *v, long new);
 int atomic64_add_unless(atomic64_t *v, long a, long u);

Original file line number	Diff line number	Diff line change
`@@ -42,7 +42,12 @@ long atomic64_sub_return(long i, atomic64_t *v);`
`42`	`42`	`#define atomic64_dec_return(v) (atomic64_sub_return(1, (v)))`
`43`	`43`	`static inline long atomic64_cmpxchg(atomic64_t *v, long old, long new)`
`44`	`44`	`{`
`45`		`- return cmpxchg(&v->counter, old, new);`
	`45`	`+ long long val;`
	`46`	`+`
	`47`	`+ val = v->counter;`
	`48`	`+ if (val == old)`
	`49`	`+ v->counter = new;`
	`50`	`+ return val;`
`46`	`51`	`}`
`47`	`52`	`long atomic64_xchg(atomic64_t *v, long new);`
`48`	`53`	`int atomic64_add_unless(atomic64_t *v, long a, long u);`