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Date:   Mon, 26 Nov 2018 16:08:40 +0100
From:   Boris Brezillon <boris.brezillon@bootlin.com>
To:     Naresh Kamboju <naresh.kamboju@linaro.org>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        open list <linux-kernel@vger.kernel.org>,
        linux- stable <stable@vger.kernel.org>,
        nicolas.ferre@microchip.com, rainyfeeling@outlook.com,
        johan@kernel.org
Subject: Re: [PATCH 4.14 58/62] mtd: rawnand: atmel: fix OF child-node
 lookup
Message-ID: <20181126160840.1c702e87@bbrezillon>
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On Mon, 26 Nov 2018 19:46:15 +0530
Naresh Kamboju <naresh.kamboju@linaro.org> wrote:

> Do you see build failure arm x15 beagleboard on 4.14 due to this patch ?
> 
> On Mon, 26 Nov 2018 at 16:31, Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> >
> > 4.14-stable review patch.  If anyone has any objections, please let me know.
> >
> > ------------------
> >
> > From: Johan Hovold <johan@kernel.org>
> >
> > commit 5d1e9c2212ea6b4dd735e4fc3dd6279a365d5d10 upstream.
> >
> > Use the new of_get_compatible_child() helper to lookup the nfc child
> > node instead of using of_find_compatible_node(), which searches the
> > entire tree from a given start node and thus can return an unrelated
> > (i.e. non-child) node.
> >
> > This also addresses a potential use-after-free (e.g. after probe
> > deferral) as the tree-wide helper drops a reference to its first
> > argument (i.e. the node of the device being probed).
> >
> > While at it, also fix a related nfc-node reference leak.
> >
> > Fixes: f88fc122cc34 ("mtd: nand: Cleanup/rework the atmel_nand driver")
> > Cc: stable <stable@vger.kernel.org>     # 4.11
> > Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
> > Cc: Josh Wu <rainyfeeling@outlook.com>
> > Cc: Boris Brezillon <boris.brezillon@bootlin.com>
> > Signed-off-by: Johan Hovold <johan@kernel.org>
> > Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
> > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> >
> > ---
> >  drivers/mtd/nand/atmel/nand-controller.c |   11 +++++++----
> >  1 file changed, 7 insertions(+), 4 deletions(-)
> >
> > --- a/drivers/mtd/nand/atmel/nand-controller.c
> > +++ b/drivers/mtd/nand/atmel/nand-controller.c
> > @@ -2077,8 +2077,7 @@ atmel_hsmc_nand_controller_legacy_init(s
> >         int ret;
> >
> >         nand_np = dev->of_node;
> > -       nfc_np = of_find_compatible_node(dev->of_node, NULL,
> > -                                        "atmel,sama5d3-nfc");
> > +       nfc_np = of_get_compatible_child(dev->of_node, "atmel,sama5d3-nfc");
> >         if (!nfc_np) {
> >                 dev_err(dev, "Could not find device node for sama5d3-nfc\n");
> >                 return -ENODEV;
> > @@ -2492,15 +2491,19 @@ static int atmel_nand_controller_probe(s
> >         }
> >
> >         if (caps->legacy_of_bindings) {
> > +               struct device_node *nfc_node;
> >                 u32 ale_offs = 21;
> >
> >                 /*
> >                  * If we are parsing legacy DT props and the DT contains a
> >                  * valid NFC node, forward the request to the sama5 logic.
> >                  */
> > -               if (of_find_compatible_node(pdev->dev.of_node, NULL,
> > -                                           "atmel,sama5d3-nfc"))
> > +               nfc_node = of_get_compatible_child(pdev->dev.of_node,
> > +                                                  "atmel,sama5d3-nfc");
> > +               if (nfc_node) {
> >                         caps = &atmel_sama5_nand_caps;
> > +                       of_node_put(nfc_node);
> > +               }
> >
> >                 /*
> >                  * Even if the compatible says we are dealing with an
> >
> >  
> 
> /drivers/mtd/nand/atmel/nand-controller.c: In function
> 'atmel_hsmc_nand_controller_legacy_init':
> /drivers/mtd/nand/atmel/nand-controller.c:2080:11: error: implicit
> declaration of function 'of_get_compatible_child'; did you mean
> 'of_get_next_available_child'? [-Werror=implicit-function-declaration]
>    nfc_np = of_get_compatible_child(dev->of_node, "atmel,sama5d3-nfc");

Looks like of_get_compatible_child() has been introduced in 4.18, hence
this error.

Greg, can you drop this patch from 4.14.y?