From: yangsheng <ys@whamcloud.com>
Date: Thu, 22 Mar 2012 02:16:14 +0000 (+0800)
Subject: LU-506 kernel: remove unnecessary memset from autoconf test
X-Git-Tag: 2.2.51~20
X-Git-Url: https://git.whamcloud.com/?p=fs%2Flustre-release.git;a=commitdiff_plain;h=931ae518f564c2ea16677f176dbaa0da2c28897a

LU-506 kernel: remove unnecessary memset from autoconf test

Eliminate memset() usage from config check. It may introduces
its own compiler error on some systems.

Signed-off-by: yang sheng <ys@whamcloud.com>
Change-Id: I1e6eae772782b3dbeab75230bfa41e781c4c4028
Reviewed-on: http://review.whamcloud.com/2336
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Jinshan Xiong <jinshan.xiong@whamcloud.com>
Tested-by: Hudson
Reviewed-by: Oleg Drokin <green@whamcloud.com>
---

diff --git a/lustre/autoconf/lustre-core.m4 b/lustre/autoconf/lustre-core.m4
index 4818462..9c84f41 100644
--- a/lustre/autoconf/lustre-core.m4
+++ b/lustre/autoconf/lustre-core.m4
@@ -1400,8 +1400,7 @@ LB_LINUX_TRY_COMPILE([
         #include <linux/exportfs.h>
 #endif
 ],[
-        struct export_operations exp;
-        memset(exp.fh_to_dentry, 0, sizeof(exp.fh_to_dentry));
+        do{ }while(sizeof(((struct export_operations *)0)->fh_to_dentry));
 ], [
         AC_MSG_RESULT([yes])
         AC_DEFINE(HAVE_FH_TO_DENTRY, 1,
@@ -1449,11 +1448,9 @@ LB_LINUX_TRY_COMPILE([
         #include <linux/spinlock.h>
         #include <linux/fs_struct.h>
 ],[
-        struct path path;
         struct fs_struct fs;
 
-        fs.pwd = path;
-        memset(&fs, 0, sizeof(fs));
+        fs.pwd = *((struct path *)sizeof(fs));
 ], [
         AC_MSG_RESULT([yes])
         AC_DEFINE(HAVE_FS_STRUCT_USE_PATH, 1,
@@ -2064,8 +2061,7 @@ AC_DEFUN([LC_REQUEST_QUEUE_UNPLUG_FN],
 LB_LINUX_TRY_COMPILE([
         #include <linux/blkdev.h>
 ],[
-        struct request_queue rq;
-        memset(rq.unplug_fn, 0, sizeof(rq.unplug_fn));
+        do{ }while(sizeof(((struct request_queue *)0)->unplug_fn));
 ],[
         AC_DEFINE(HAVE_REQUEST_QUEUE_UNPLUG_FN, 1,
                   [request_queue has unplug_fn field])