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From:   Jason Yan <yanaijie@huawei.com>
To:     <jaegeuk@kernel.org>, <chao@kernel.org>,
        <linux-f2fs-devel@lists.sourceforge.net>,
        <linux-kernel@vger.kernel.org>
CC:     <kernel-hardening@lists.openwall.com>,
        Jason Yan <yanaijie@huawei.com>,
        Kees Cook <keescook@chromium.org>, Chao Yu <yuchao0@huawei.com>
Subject: [PATCH] f2fs: Eliminate usage of uninitialized_var() macro
Date:   Mon, 15 Jun 2020 16:51:32 +0800
Message-ID: <20200615085132.166470-1-yanaijie@huawei.com>
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This is an effort to eliminate the uninitialized_var() macro[1].

The use of this macro is the wrong solution because it forces off ANY
analysis by the compiler for a given variable. It even masks "unused
variable" warnings.

Quoted from Linus[2]:

"It's a horrible thing to use, in that it adds extra cruft to the
source code, and then shuts up a compiler warning (even the _reliable_
warnings from gcc)."

Fix it by remove this variable since it is not needed at all.

[1] https://github.com/KSPP/linux/issues/81
[2] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/

Cc: Kees Cook <keescook@chromium.org>
Suggested-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
---
 v2: Directly remove this variable.

 fs/f2fs/data.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 326c63879ddc..3753ba06531b 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -2856,7 +2856,6 @@ static int f2fs_write_cache_pages(struct address_space *mapping,
 	};
 #endif
 	int nr_pages;
-	pgoff_t uninitialized_var(writeback_index);
 	pgoff_t index;
 	pgoff_t end;		/* Inclusive */
 	pgoff_t done_index;
@@ -2875,8 +2874,7 @@ static int f2fs_write_cache_pages(struct address_space *mapping,
 		clear_inode_flag(mapping->host, FI_HOT_DATA);
 
 	if (wbc->range_cyclic) {
-		writeback_index = mapping->writeback_index; /* prev offset */
-		index = writeback_index;
+		index = mapping->writeback_index; /* prev offset */
 		end = -1;
 	} else {
 		index = wbc->range_start >> PAGE_SHIFT;
-- 
2.25.4