On Thu, May 29, 2014 at 02:03:37PM -0700, Andrew Morton wrote:
> On Tue, 27 May 2014 22:23:51 +0200 Rickard Strandqvist
> <rickard_strandqv...@spectrumdigital.se> wrote:
>
> > Removal of null pointer checks that could never happen
>
> How do you know it never happens?
>
> > --- a/fs/ocfs2/move_extents.c
> > +++ b/fs/ocfs2/move_extents.c
> > @@ -904,9 +904,6 @@ static int ocfs2_move_extents(struct
> > ocfs2_move_extents_context *context)
> > struct buffer_head *di_bh = NULL;
> > struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
> >
> > - if (!inode)
> > - return -ENOENT;
> > -
>
> If it's due to assuming that the previous statement would have oopsed
> then that is mistaken. Is is sometimes the case that gcc will move the
> evaluation of inode->i_sb to after the test, so this function can be
> passed NULL and it will not oops.
'sometimes' ?
You have a lot more faith in gcc than I do. What happens if we decide to
switch to llvm one day ? Can we guarantee every compiler will implement
the same magic ? This seems fragile as hell to me.
Dave
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