Relying on an unchecked of_iomap() which can return NULL is problematic
here, an explicit check seems mandatory. Also the call to
of_find_compatible_node() returns a device node with refcount incremented
therefor an explicit of_node_put() is needed here. 

Signed-off-by: Nicholas Mc Guire <hof...@osadl.org>
Fixes: commit 22bae4290457 ("ARM: hi3xxx: add hotplug support")
---

Problem found by an experimental coccinelle script

The way  id  is used is a bit redundant with the function return - not
really clear if this "double indication" is intentional or just happened ?
Also note that hi3xxx_hotplug_init probably should be bool as that is how
it is being used - the error return is not actually interpreted beyond
detection of failure in its only call site hi3xxx_set_cpu().

Patch was compile tested with: hisi_defconfig (implies CONFIG_SMP=y)

Patch is against 4.18-rc3 (localversion-next is next-20180712)

 arch/arm/mach-hisi/hotplug.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/arch/arm/mach-hisi/hotplug.c b/arch/arm/mach-hisi/hotplug.c
index 40857bf..4036ffe 100644
--- a/arch/arm/mach-hisi/hotplug.c
+++ b/arch/arm/mach-hisi/hotplug.c
@@ -148,13 +148,20 @@ static int hi3xxx_hotplug_init(void)
        struct device_node *node;
 
        node = of_find_compatible_node(NULL, NULL, "hisilicon,sysctrl");
-       if (node) {
-               ctrl_base = of_iomap(node, 0);
-               id = HI3620_CTRL;
-               return 0;
+       if (!node) {
+               id = ERROR_CTRL;
+               return -ENOENT;
        }
-       id = ERROR_CTRL;
-       return -ENOENT;
+
+       ctrl_base = of_iomap(node, 0);
+       of_node_put(node);
+       if (!ctrl_base) {
+               id = ERROR_CTRL;
+               return -ENOMEM;
+       }
+
+       id = HI3620_CTRL;
+       return 0;
 }
 
 void hi3xxx_set_cpu(int cpu, bool enable)
-- 
2.1.4

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