Re: [PATCH v3 2/3] mm, swap: reduce indention for hibernate allocation helper

[Barry Song <21cnbao@gmail.com>]

On Mon, Feb 16, 2026 at 2:21 PM Kairui Song <ryncsn@gmail.com> wrote:
>
> On Mon, Feb 16, 2026 at 07:20:49AM +0800, Barry Song wrote:
> > On Mon, Feb 16, 2026 at 3:00 AM Kairui Song via B4 Relay
> > <devnull+kasong.tencent.com@kernel.org> wrote:
> > >
> > > From: Kairui Song <kasong@tencent.com>
> > >
> > > It doesn't have to check the device flag, as the allocator will also
> > > check the device flag and refuse to allocate if the device is not
> > > writable. This might cause a trivial waste of CPU cycles of hibernate
> > > allocation raced with swapoff, but that is very unlikely to happen.
> > > Removing the check on the common path should be more helpful.
> > >
> > > Signed-off-by: Kairui Song <kasong@tencent.com>
> > > ---
> > >  mm/swapfile.c | 38 ++++++++++++++++++--------------------
> > >  1 file changed, 18 insertions(+), 20 deletions(-)
> > >
> > > diff --git a/mm/swapfile.c b/mm/swapfile.c
> > > index 32e0e7545ab8..0d1b17c99221 100644
> > > --- a/mm/swapfile.c
> > > +++ b/mm/swapfile.c
> > > @@ -1936,27 +1936,25 @@ swp_entry_t swap_alloc_hibernation_slot(int type)
> > >
> > >         /* This is called for allocating swap entry, not cache */
> > >         if (get_swap_device_info(si)) {
> >
> >
> > I guess we could further reduce indentation by doing:
> > if (!get_swap_device_info(si))
> >     goto fail;
> >
>
> Agree, I think we can make it even simpler by having:
>
> /* Return empty entry if device is not usable (swapoff or full) */
> if (!si || !get_swap_device_info(si))
>         return entry;
>
> Then the `fail` label is also gone.

Yes, this looks even nicer to me. :-)

>
> I'll post a v4 later today combined with your another suggestion. Thanks!