[PATCH V2] ARM: STi: warn if scu mapping fails

From: Nicholas Mc Guire
Date: Mon Jul 16 2018 - 09:51:31 EST


If the device node is not found or the of_iomap() failed, calling
scu_enable would not be safe and could lead to an undefined system
state. So warn in both failure paths before returning.

Signed-off-by: Nicholas Mc Guire <hofrat@xxxxxxxxx>
Link: http://lkml.org/lkml/2018/7/16/219
Fixes: commit 65ebcc115889 ("ARM: sti: Add STiH415 SOC support")
---

V2: replacement of WARN_ON() by a meaningful pr_err as suggested by
Patrice CHOTARD <patrice.chotard@xxxxxx>.

Problem was found by an experimental coccinelle script

Patch was compile tested with: multi_v7_defconfig (implies
CONFIG_ARCH_STI=y, CONFIG_SMP=y)
(with one sparse warning unrelated to the proposed change)

Patch is against 4.18-rc4 (localversion-next is next-20180716)

arch/arm/mach-sti/platsmp.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/arch/arm/mach-sti/platsmp.c b/arch/arm/mach-sti/platsmp.c
index 231f19e..530e9a5 100644
--- a/arch/arm/mach-sti/platsmp.c
+++ b/arch/arm/mach-sti/platsmp.c
@@ -107,12 +107,22 @@ static void __init sti_smp_prepare_cpus(unsigned int max_cpus)

np = of_find_compatible_node(NULL, NULL, "arm,cortex-a9-scu");

- if (np) {
- scu_base = of_iomap(np, 0);
- scu_enable(scu_base);
- of_node_put(np);
+ if (!np) {
+ pr_err("SCU not found at %s:%s():%d\n",
+ __FILE__, __func__, __LINE__);
+ return;
}

+ scu_base = of_iomap(np, 0);
+ of_node_put(np);
+ if (!scu_base) {
+ pr_err("SCU remap failed at %s:%s():%d\n",
+ __FILE__, __func__, __LINE__);
+ return;
+ }
+
+ scu_enable(scu_base);
+
if (max_cpus <= 1)
return;

--
2.1.4