[PATCH] staging: board: drop refcount in success case

[PATCH] staging: board: drop refcount in success case

[Nicholas Mc Guire]

 The call to of_find_compatible_node() returns irqc_node with refcount
incremented thus it must be explicitly decremented here after it was
checked for non-NULL.

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Fixes: commit 72ee8626eeb1 ("staging: board: Add support for translating hwirq to virq numbers")
---

Problem located with an experimental coccinelle script

Patch was compile-tested with: x86_64_defconfig + STAGING=y, STAGING_BOARD=y

Patch is against 4.18-rc1 (localversion-next is next-20180618)

 drivers/staging/board/board.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/staging/board/board.c b/drivers/staging/board/board.c
index cb6feb3..8ee48e5 100644
--- a/drivers/staging/board/board.c
+++ b/drivers/staging/board/board.c
@@ -64,12 +64,13 @@ int __init board_staging_gic_setup_xlate(const char *gic_match,
 	irqc_node = of_find_compatible_node(NULL, NULL, gic_match);
 
 	WARN_ON(!irqc_node);
 	if (!irqc_node)
 		return -ENOENT;
 
+	of_node_put(irqc_node);
 	irqc_base = base;
 	return 0;
 }
 
 static void __init gic_fixup_resource(struct resource *res)
 {
-- 
2.1.4

Re: [PATCH] staging: board: drop refcount in success case

[Dan Carpenter]

On Mon, Jun 18, 2018 at 08:53:19PM +0200, Nicholas Mc Guire wrote:
>  The call to of_find_compatible_node() returns irqc_node with refcount
> incremented thus it must be explicitly decremented here after it was
> checked for non-NULL.
> 
> Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
> Fixes: commit 72ee8626eeb1 ("staging: board: Add support for translating hwirq to virq numbers")
> ---
> 
> Problem located with an experimental coccinelle script
> 
> Patch was compile-tested with: x86_64_defconfig + STAGING=y, STAGING_BOARD=y
> 
> Patch is against 4.18-rc1 (localversion-next is next-20180618)
> 
>  drivers/staging/board/board.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/staging/board/board.c b/drivers/staging/board/board.c
> index cb6feb3..8ee48e5 100644
> --- a/drivers/staging/board/board.c
> +++ b/drivers/staging/board/board.c
> @@ -64,12 +64,13 @@ int __init board_staging_gic_setup_xlate(const char *gic_match,
>  	irqc_node = of_find_compatible_node(NULL, NULL, gic_match);
>  
>  	WARN_ON(!irqc_node);
>  	if (!irqc_node)
>  		return -ENOENT;
>  
> +	of_node_put(irqc_node);

I don't feel like this is the right thing...  We should keep the
reference until we're done with it.  Which apparently is never?

But I don't know the code at all so I could be wrong.

regards,
dan carpenter

Re: [PATCH] staging: board: drop refcount in success case

[Geert Uytterhoeven]

On Tue, Jun 19, 2018 at 9:37 AM Dan Carpenter <dan.carpenter@oracle.com> wrote:
> On Mon, Jun 18, 2018 at 08:53:19PM +0200, Nicholas Mc Guire wrote:
> >  The call to of_find_compatible_node() returns irqc_node with refcount
> > incremented thus it must be explicitly decremented here after it was
> > checked for non-NULL.
> >
> > Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
> > Fixes: commit 72ee8626eeb1 ("staging: board: Add support for translating hwirq to virq numbers")
> > ---
> >
> > Problem located with an experimental coccinelle script
> >
> > Patch was compile-tested with: x86_64_defconfig + STAGING=y, STAGING_BOARD=y
> >
> > Patch is against 4.18-rc1 (localversion-next is next-20180618)
> >
> >  drivers/staging/board/board.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/staging/board/board.c b/drivers/staging/board/board.c
> > index cb6feb3..8ee48e5 100644
> > --- a/drivers/staging/board/board.c
> > +++ b/drivers/staging/board/board.c
> > @@ -64,12 +64,13 @@ int __init board_staging_gic_setup_xlate(const char *gic_match,
> >       irqc_node = of_find_compatible_node(NULL, NULL, gic_match);
> >
> >       WARN_ON(!irqc_node);
> >       if (!irqc_node)
> >               return -ENOENT;
> >
> > +     of_node_put(irqc_node);
>
> I don't feel like this is the right thing...  We should keep the
> reference until we're done with it.  Which apparently is never?

Indeed. The reference must not be released in this function, as it's stored in
a global variable, and used later.

As all users are __init, it could be released when the init section is freeed,
in theory, but there's no callback for that.

Hence:
NAKed-by: Geert Uytterhoeven <geert+renesas@glider.be>

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH] staging: board: drop refcount in success case

[Nicholas Mc Guire]

On Tue, Jun 19, 2018 at 09:51:44AM +0200, Geert Uytterhoeven wrote:
> On Tue, Jun 19, 2018 at 9:37 AM Dan Carpenter <dan.carpenter@oracle.com> wrote:
> > On Mon, Jun 18, 2018 at 08:53:19PM +0200, Nicholas Mc Guire wrote:
> > >  The call to of_find_compatible_node() returns irqc_node with refcount
> > > incremented thus it must be explicitly decremented here after it was
> > > checked for non-NULL.
> > >
> > > Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
> > > Fixes: commit 72ee8626eeb1 ("staging: board: Add support for translating hwirq to virq numbers")
> > > ---
> > >
> > > Problem located with an experimental coccinelle script
> > >
> > > Patch was compile-tested with: x86_64_defconfig + STAGING=y, STAGING_BOARD=y
> > >
> > > Patch is against 4.18-rc1 (localversion-next is next-20180618)
> > >
> > >  drivers/staging/board/board.c | 1 +
> > >  1 file changed, 1 insertion(+)
> > >
> > > diff --git a/drivers/staging/board/board.c b/drivers/staging/board/board.c
> > > index cb6feb3..8ee48e5 100644
> > > --- a/drivers/staging/board/board.c
> > > +++ b/drivers/staging/board/board.c
> > > @@ -64,12 +64,13 @@ int __init board_staging_gic_setup_xlate(const char *gic_match,
> > >       irqc_node = of_find_compatible_node(NULL, NULL, gic_match);
> > >
> > >       WARN_ON(!irqc_node);
> > >       if (!irqc_node)
> > >               return -ENOENT;
> > >
> > > +     of_node_put(irqc_node);
> >
> > I don't feel like this is the right thing...  We should keep the
> > reference until we're done with it.  Which apparently is never?
> 
> Indeed. The reference must not be released in this function, as it's stored in
> a global variable, and used later.

yup -  I had simply interpreted this incorrectly as checking only and
overlooked that this was a global variable.

> 
> As all users are __init, it could be released when the init section is freeed,
> in theory, but there's no callback for that.
> 
> Hence:
> NAKed-by: Geert Uytterhoeven <geert+renesas@glider.be>
>
thanks for the clarification - sorry for the noise.

thx
hofrat