Re: [PATCH] btrfs: initialize variable cancel

[Wang Yugui <wangyugui@e16-tech.com>]

Hi,

Mabye we should enable '-Wmaybe-uninitialized' for btrfs 'make W=1'.

There is another warning  reproted by '-Wmaybe-uninitialized' 
in btrfs misc-next.

fs/btrfs/zoned.c:273:28: warning: ‘zno’ may be used uninitialized in this function [-Wmaybe-uninitialized]
   memcpy(zinfo->zone_cache + zno, zones,
                            ^

diff --git a/fs/btrfs/Makefile b/fs/btrfs/Makefile
index cec88a6..f1052ce 100644
--- a/fs/btrfs/Makefile
+++ b/fs/btrfs/Makefile
@@ -2,6 +2,7 @@
 
 # Subset of W=1 warnings
 subdir-ccflags-y += -Wextra -Wunused -Wno-unused-parameter
+subdir-ccflags-y += -Wmaybe-uninitialized
 subdir-ccflags-y += -Wmissing-declarations
 subdir-ccflags-y += -Wmissing-format-attribute
 subdir-ccflags-y += -Wmissing-prototypes

Best Regards
Wang Yugui (wangyugui@e16-tech.com)
2022/01/25

> From: Tom Rix <trix@redhat.com>
> 
> Clang static analysis reports this problem
> ioctl.c:3333:8: warning: 3rd function call argument is an
>   uninitialized value
>     ret = exclop_start_or_cancel_reloc(fs_info,
> 
> cancel is only set in one branch of an if-check and is
> always used.  So initialize to false.
> 
> Fixes: 1a15eb724aae ("btrfs: use btrfs_get_dev_args_from_path in dev removal ioctls")
> Signed-off-by: Tom Rix <trix@redhat.com>
> ---
>  fs/btrfs/ioctl.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 190ad8af4f45a..26e82379747f8 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -3308,7 +3308,7 @@ static long btrfs_ioctl_rm_dev(struct file *file, void __user *arg)
>  	struct block_device *bdev = NULL;
>  	fmode_t mode;
>  	int ret;
> -	bool cancel;
> +	bool cancel = false;
>  
>  	if (!capable(CAP_SYS_ADMIN))
>  		return -EPERM;
> -- 
> 2.26.3