linux-kernel - Re: [PATCH] fpga: region: release of_parse

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Date:   Fri, 27 Oct 2017 13:26:31 -0500
From:   Alan Tull <atull@...nel.org>
To:     Ian Abbott <abbotti@....co.uk>
Cc:     linux-fpga@...r.kernel.org, Moritz Fischer <mdf@...nel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        "# 4 . 10+" <stable@...r.kernel.org>
Subject: Re: [PATCH] fpga: region: release of_parse_phandle nodes after use

On Fri, Oct 27, 2017 at 11:56 AM, Ian Abbott <abbotti@....co.uk> wrote:

Hi Ian,

Looks good.  Thanks for catching this!

Alan

> Both fpga_region_get_manager() and fpga_region_get_bridges() call
> of_parse_phandle(), but nothing calls of_node_put() on the returned
> struct device_node pointers.  Make sure to do that to stop their
> reference counters getting out of whack.
>
> Fixes: 0fa20cdfcc1f ("fpga: fpga-region: device tree control for FPGA")
> Cc: <stable@...r.kernel.org> # 4.10+
> Signed-off-by: Ian Abbott <abbotti@....co.uk>

Signed-off-by: Alan Tull <atull@...nel.org>

> ---
>  drivers/fpga/fpga-region.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/fpga/fpga-region.c b/drivers/fpga/fpga-region.c
> index d9ab7c75b14f..e0c73ceba2ed 100644
> --- a/drivers/fpga/fpga-region.c
> +++ b/drivers/fpga/fpga-region.c
> @@ -147,6 +147,7 @@ static struct fpga_manager *fpga_region_get_manager(struct fpga_region *region)
>                         mgr_node = of_parse_phandle(np, "fpga-mgr", 0);
>                         if (mgr_node) {
>                                 mgr = of_fpga_mgr_get(mgr_node);
> +                               of_node_put(mgr_node);
>                                 of_node_put(np);
>                                 return mgr;
>                         }
> @@ -192,10 +193,13 @@ static int fpga_region_get_bridges(struct fpga_region *region,
>                 parent_br = region_np->parent;
>
>         /* If overlay has a list of bridges, use it. */
> -       if (of_parse_phandle(overlay, "fpga-bridges", 0))
> +       br = of_parse_phandle(overlay, "fpga-bridges", 0);
> +       if (br) {
> +               of_node_put(br);
>                 np = overlay;
> -       else
> +       } else {
>                 np = region_np;
> +       }
>
>         for (i = 0; ; i++) {
>                 br = of_parse_phandle(np, "fpga-bridges", i);
> @@ -203,12 +207,15 @@ static int fpga_region_get_bridges(struct fpga_region *region,
>                         break;
>
>                 /* If parent bridge is in list, skip it. */
> -               if (br == parent_br)
> +               if (br == parent_br) {
> +                       of_node_put(br);
>                         continue;
> +               }
>
>                 /* If node is a bridge, get it and add to list */
>                 ret = fpga_bridge_get_to_list(br, region->info,
>                                               &region->bridge_list);
> +               of_node_put(br);
>
>                 /* If any of the bridges are in use, give up */
>                 if (ret == -EBUSY) {
> --
> 2.14.2
>