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Subject[PATCH] erofs: Eliminate usage of uninitialized_var() macro
Date
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
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