Fix atomic_sub_64() i386 assembly implementation

The atomic_sub_64() should use sbbl instead of adcl. In user space these atomics are used for statistics tracking and aren't critical which explain how this was overlooked. The kernel space implementation of these atomics are layered on the architecture specific implementations provided by the kernel. Signed-off-by: Brian Behlendorf <[email protected]> Issue openzfs#5671
behlendorf · Jan 31, 2017 · 2695051 · 2695051
1 parent e245489
commit 2695051
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/lib/libspl/asm-i386/atomic.S b/lib/libspl/asm-i386/atomic.S
@@ -507,7 +507,7 @@
 	movl	16(%esp), %ebx
 	movl	20(%esp), %ecx
 	subl	%eax, %ebx
-	adcl	%edx, %ecx
+	sbbl	%edx, %ecx
 	lock
 	cmpxchg8b (%edi)
 	jne	1b