Fix RWSEM_SPINLOCK_IS_RAW check failed

Initialize dummy_lock to fix the build error in gcc 7.1.1 with:
  error: ‘dummy_lock’ is used uninitialized in this function

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Closes #622

diff --git a/config/spl-build.m4 b/config/spl-build.m4
index 7569988daee87b4fd49329e191bb8fa806e01da6..698d51a87f276c45650607cee5d3750503bd0004 100644 (file)
--- a/config/spl-build.m4
+++ b/config/spl-build.m4
@@ -1313,7 +1313,8 @@ AC_DEFUN([SPL_AC_RWSEM_SPINLOCK_IS_RAW], [
                #include <linux/rwsem.h>
        ],[
                struct rw_semaphore dummy_semaphore __attribute__ ((unused));
-               raw_spinlock_t dummy_lock __attribute__ ((unused));
+               raw_spinlock_t dummy_lock __attribute__ ((unused)) =
+                   __RAW_SPIN_LOCK_INITIALIZER(dummy_lock);
                dummy_semaphore.wait_lock = dummy_lock;
        ],[
                AC_MSG_RESULT(yes)