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btrfs-progs: check/lowmem: Fix a false alert on uninitialized value

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[BUG]
When compiling the devel branch with commit fb8f05e40b458
("btrfs-progs: check: Make repair_imode_common() handle inodes in
subvolume trees"), the following warning will be reported:

  check/mode-common.c: In function ‘detect_imode’:
  check/mode-common.c|1071 col 23| warning: ‘imode’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  1071 |   *imode_ret = (imode | 0700);
       |                ~~~~~~~^~~~~~~

This only occurs for regular build. If compiled with D=1, the warning
just disappears.

[CAUSE]
Looks like a bug in gcc optimization.
The code will only set @imode_ret when @found is true.
And for every "found = true" assignment we have assigned @imode.
So this is just a false alert.

[FIX]
I hope I can fix the problem of GCC, but obviously I can't (at least for
now).

So let's assign an initial value 0 to @imode to suppress the false
alert.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2019-11-18 14:30:49 +08:00 committed by David Sterba
parent 97fc76c0ac
commit 36128dff44
1 changed files with 1 additions and 1 deletions
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2
check/mode-common.c
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@ -972,7 +972,7 @@ int detect_imode(struct btrfs_root *root, struct btrfs_path *path,
struct btrfs_inode_item iitem;
bool found = false;
u64 ino;
u32 imode;
u32 imode = 0;
int ret = 0;
btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);