[PATCH] kexec jump: fix compiling warning on xchg(&kexec_lock, 0) in kernel_kexec()

[Huang Ying]

Fix compiling warning on xchg(&kexec_lock, 0) in kernel_kexec().

Signed-off-by: Huang Ying <ying.huang at intel.com>

---
 kernel/kexec.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -1433,6 +1433,7 @@ module_init(crash_save_vmcoreinfo_init)
 int kernel_kexec(void)
 {
 	int error = 0;
+	int locked;
 
 	if (xchg(&kexec_lock, 1))
 		return -EBUSY;
@@ -1498,7 +1499,8 @@ int kernel_kexec(void)
 #endif
 
  Unlock:
-	xchg(&kexec_lock, 0);
+	locked = xchg(&kexec_lock, 0);
+	BUG_ON(!locked);
 
 	return error;
 }