Re: [PATCH] btrfs: Turn an 'else if' into an 'else' in btrfs_uuid_tree_add

[Nick Desaulniers]

On Thu, Mar 7, 2019 at 9:54 AM David Sterba <dsterba@xxxxxxx> wrote:
>
> On Thu, Mar 07, 2019 at 09:35:15AM -0700, Nathan Chancellor wrote:
> > When building with -Wsometimes-uninitialized, Clang warns:
> >
> > fs/btrfs/uuid-tree.c:129:13: warning: variable 'eb' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
> > fs/btrfs/uuid-tree.c:129:13: warning: variable 'offset' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
> >
> > Clang can't tell that all cases are covered with this final else if.
>
> The chain of conditions is
>
> if (ret >= 0)
> else if (ret == -EEXIST)
> else if (ret < 0)

In the few cases we looked at, it seemed that the compiler's heuristic
for coverage doesn't try very hard.  I assume once you start having
more complicated expressions is gets quite difficult to prove.

Thanks for the patch Nathan!
-- 
Thanks,
~Nick Desaulniers