[PATCH] atomic: cmpxchg

[mirror_ubuntu-jammy-kernel.git] / arch / sparc / lib / atomic32.c

diff --git a/arch/sparc/lib/atomic32.c b/arch/sparc/lib/atomic32.c
index 2e64e8c3e8e54c1aafbe66e34d3d64cf0f96f895..be46f65451846af2eef721a0c1d111082cbeec86 100644 (file)
--- a/arch/sparc/lib/atomic32.c
+++ b/arch/sparc/lib/atomic32.c
@@ -37,17 +37,28 @@ int __atomic_add_return(int i, atomic_t *v)
        spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
        return ret;
 }
+EXPORT_SYMBOL(__atomic_add_return);
 
-void atomic_set(atomic_t *v, int i)
+int atomic_cmpxchg(atomic_t *v, int old, int new)
 {
+       int ret;
        unsigned long flags;
-       spin_lock_irqsave(ATOMIC_HASH(v), flags);
 
-       v->counter = i;
+       spin_lock_irqsave(ATOMIC_HASH(v), flags);
+       ret = v->counter;
+       if (likely(ret == old))
+               v->counter = new;
 
        spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
+       return ret;
 }
 
-EXPORT_SYMBOL(__atomic_add_return);
-EXPORT_SYMBOL(atomic_set);
+void atomic_set(atomic_t *v, int i)
+{
+       unsigned long flags;
 
+       spin_lock_irqsave(ATOMIC_HASH(v), flags);
+       v->counter = i;
+       spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
+}
+EXPORT_SYMBOL(atomic_set);