Messages in this thread | | | Date | Thu, 29 May 2014 17:23:08 -0400 | From | Dave Jones <> | Subject | Re: [PATCH] fs: ocfs2: move_extents.c: Fix to remove null pointer checks that could never happen |
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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_strandqvist@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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