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References: <20240522194250.1165568-1-pvkumar5749404@gmail.com> <87h6eo3h4i.fsf@mail.lhotse>
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From: prabhav kumar <pvkumar5749404@gmail.com>
Date: Thu, 23 May 2024 23:31:40 +0530
Message-ID: <CAH8oh8UP=U11XJWoDWf2wRb08PZk0LuCiYMygWSmcYtZ3Yh3mA@mail.gmail.com>
Subject: Re: [PATCH next] arch: powerpc: platforms: Remove unnecessary call to of_node_get
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: akpm@linux-foundation.org, npiggin@gmail.com, christophe.leroy@csgroup.eu, 
	naveen.n.rao@linux.ibm.com, linuxppc-dev@lists.ozlabs.org, 
	linux-kernel@vger.kernel.org, skhan@linuxfoundation.org, 
	julia.lawall@inria.fr, javier.carrasco.cruz@gmail.com
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On Thu, May 23, 2024 at 4:55=E2=80=AFPM Michael Ellerman <mpe@ellerman.id.a=
u> wrote:
>
> Prabhav Kumar Vaish <pvkumar5749404@gmail.com> writes:
> > `dev->of_node` has a pointer to device node, of_node_get call seems
> > unnecessary.
>
> Sorry but it is necessary.
>
> > Signed-off-by: Prabhav Kumar Vaish <pvkumar5749404@gmail.com>
> > ---
> >  arch/powerpc/platforms/cell/iommu.c | 9 +++------
> >  1 file changed, 3 insertions(+), 6 deletions(-)
> >
> > diff --git a/arch/powerpc/platforms/cell/iommu.c b/arch/powerpc/platfor=
ms/cell/iommu.c
> > index 4cd9c0de22c2..5b794ce08689 100644
> > --- a/arch/powerpc/platforms/cell/iommu.c
> > +++ b/arch/powerpc/platforms/cell/iommu.c
> > @@ -780,14 +780,13 @@ static int __init cell_iommu_init_disabled(void)
> >  static u64 cell_iommu_get_fixed_address(struct device *dev)
> >  {
> >       u64 cpu_addr, size, best_size, dev_addr =3D OF_BAD_ADDR;
> > -     struct device_node *np;
> > +     struct device_node *np =3D dev->of_node;
> >       const u32 *ranges =3D NULL;
> >       int i, len, best, naddr, nsize, pna, range_size;
> >
> >       /* We can be called for platform devices that have no of_node */
> > -     np =3D of_node_get(dev->of_node);
> >       if (!np)
> > -             goto out;
> > +             return dev_addr;
> >
> >       while (1) {
> >               naddr =3D of_n_addr_cells(np);
>
>                 nsize =3D of_n_size_cells(np);
>                 np =3D of_get_next_parent(np);
>                 if (!np)
>                         break;
>
> of_get_next_parent() drops the reference of the node passed to it (np).
>
> So if you actually tested your patch you should see a recount underflow.
>
Thanks, I will check this out once again
Prabhav
> cheers