[PATCH] kexec warning fix

This fixes a couple of compiler warnings, and adds paranoia checks as well.

Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/kernel/kexec.c b/kernel/kexec.c
index 37cad75..fcdd5d2 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -995,7 +995,8 @@
 	image = xchg(dest_image, image);
 
 out:
-	xchg(&kexec_lock, 0); /* Release the mutex */
+	locked = xchg(&kexec_lock, 0); /* Release the mutex */
+	BUG_ON(!locked);
 	kimage_free(image);
 
 	return result;
@@ -1061,7 +1062,8 @@
 			machine_crash_shutdown(&fixed_regs);
 			machine_kexec(kexec_crash_image);
 		}
-		xchg(&kexec_lock, 0);
+		locked = xchg(&kexec_lock, 0);
+		BUG_ON(!locked);
 	}
 }