Re: [PATCH v2] maple_tree: Use correct variable type in sizeof

[Peng Zhang]

在 2023/4/11 11:42, Matthew Wilcox 写道:
> On Mon, Apr 10, 2023 at 08:29:35PM -0700, Andrew Morton wrote:
> > On Tue, 11 Apr 2023 10:35:13 +0800 Peng Zhang <zhangpeng.00@xxxxxxxxxxxxx> wrote:
> >
> > > The type of variable pointed to by pivs is unsigned long, but the type
> > > used in sizeof is a pointer type. Change it to unsigned long.
> > Thanks, but there's nothing in this changelog which explains why a
> > -stable backport is being proposed.  When fixing a bug, please always
> > describe the user-visible effects of that bug.
> There is no user-visible effect of this bug as the assembly code
> generated will be identical.

Therefore, if this has always been the case, cc stable
is also unnecessary.

> > > --- a/lib/maple_tree.c
> > > +++ b/lib/maple_tree.c
> > > @@ -3255,7 +3255,7 @@ static inline void mas_destroy_rebalance(struct ma_state *mas, unsigned char end
> > >   
> > >   		if (tmp < max_p)
> > >   			memset(pivs + tmp, 0,
> > > -			       sizeof(unsigned long *) * (max_p - tmp));
> > > +			       sizeof(unsigned long) * (max_p - tmp));
> > >   
> > >   		if (tmp < mt_slots[mt])
> > >   			memset(slots + tmp, 0, sizeof(void *) * (max_s - tmp));
> > Is there any situation in which
> > sizeof(unsigned long *) != sizeof(unsigned long)?
> Windows 64-bit (pointer 64-bit, unsigned long is 32 bit) is the only
> one I know.  Linux is all ILP32 or LP64.  There may be some embedded
> environments which are different, but I have no idea what they might be.