From: Jason Yan <yanaijie@huawei.com>
To: <xiang@kernel.org>, <chao@kernel.org>,
<gregkh@linuxfoundation.org>, <linux-erofs@lists.ozlabs.org>,
<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] erofs: Eliminate usage of uninitialized_var() macro
Date: Mon, 15 Jun 2020 12:01:41 +0800 [thread overview]
Message-ID: <20200615040141.3627746-1-yanaijie@huawei.com> (raw)
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)."
The gcc option "-Wmaybe-uninitialized" has been disabled and this change
will not produce any warnnings even with "make W=1".
[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>
Cc: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
---
fs/erofs/data.c | 4 ++--
fs/erofs/zdata.c | 2 +-
2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/fs/erofs/data.c b/fs/erofs/data.c
index 64b56c7df023..d0542151e8c4 100644
--- a/fs/erofs/data.c
+++ b/fs/erofs/data.c
@@ -265,7 +265,7 @@ static inline struct bio *erofs_read_raw_page(struct bio *bio,
*/
static int erofs_raw_access_readpage(struct file *file, struct page *page)
{
- erofs_off_t uninitialized_var(last_block);
+ erofs_off_t last_block;
struct bio *bio;
trace_erofs_readpage(page, true);
@@ -282,7 +282,7 @@ static int erofs_raw_access_readpage(struct file *file, struct page *page)
static void erofs_raw_access_readahead(struct readahead_control *rac)
{
- erofs_off_t uninitialized_var(last_block);
+ erofs_off_t last_block;
struct bio *bio = NULL;
struct page *page;
diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index be50a4d9d273..24a26aaf847f 100644
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -1161,7 +1161,7 @@ static void z_erofs_submit_queue(struct super_block *sb,
struct z_erofs_decompressqueue *q[NR_JOBQUEUES];
void *bi_private;
/* since bio will be NULL, no need to initialize last_index */
- pgoff_t uninitialized_var(last_index);
+ pgoff_t last_index;
unsigned int nr_bios = 0;
struct bio *bio = NULL;
--
2.25.4
next reply other threads:[~2020-06-15 4:01 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-15 4:01 Jason Yan [this message]
2020-06-15 7:25 ` [PATCH] erofs: Eliminate usage of uninitialized_var() macro Gao Xiang
2020-06-15 7:43 ` Jason Yan
2020-06-15 8:07 ` Gao Xiang
2020-06-15 8:29 ` Chao Yu
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