On 14 April 2013 01:43, Francesco Lavra <francescolavra.fl@xxxxxxxxx> wrote:
>> + for_each_child_of_node(of_find_node_by_path("/cpus"), np) {
>
> If of_find_node_by_path() returns NULL, there will be a NULL pointer
> dereference.
>
>> + if (count++ != cpu_dev->id)
>> + continue;
>> + if (!of_get_property(np, "operating-points", NULL))
>> + return -ENODATA;
>> +
>> + cpu_dev->of_node = np;
>> +
>> + ret = of_init_opp_table(cpu_dev);
>> + if (ret)
>> + return ret;
>> +
>> + return 0;
>
> of_node_put() should be called on np before returning.
> Also, the reference count of the parent node should be decremented as well.
>
> These comments apply to the below function dt_get_transition_latency() too.
Thanks Francesco.
Below fixes this (I will send it separately to Rafael):
Subject: [PATCH 1/2] cpufreq: ARM big LITTLE: put DT nodes after using them
DT nodes should be put using of_node_put() to balance their usage counts. This
is not done properly in ARM's big LITTLE driver. Fix it.
Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
---
drivers/cpufreq/arm_big_little_dt.c | 43 +++++++++++++++++++++++++------------
1 file changed, 29 insertions(+), 14 deletions(-)
diff --git a/drivers/cpufreq/arm_big_little_dt.c
b/drivers/cpufreq/arm_big_little_dt.c
index 452ff46..44be311 100644
--- a/drivers/cpufreq/arm_big_little_dt.c
+++ b/drivers/cpufreq/arm_big_little_dt.c
@@ -31,22 +31,28 @@
static int dt_init_opp_table(struct device *cpu_dev)
{
- struct device_node *np = NULL;
+ struct device_node *np, *parent;
int count = 0, ret;
- for_each_child_of_node(of_find_node_by_path("/cpus"), np) {
+ parent = of_find_node_by_path("/cpus");
+ if (!parent) {
+ pr_err("failed to find OF /cpus\n");
+ return -ENOENT;
+ }
+
+ for_each_child_of_node(parent, np) {
if (count++ != cpu_dev->id)
continue;
- if (!of_get_property(np, "operating-points", NULL))
- return -ENODATA;
-
- cpu_dev->of_node = np;
-
- ret = of_init_opp_table(cpu_dev);
- if (ret)
- return ret;
-
- return 0;
+ if (!of_get_property(np, "operating-points", NULL)) {
+ ret = -ENODATA;
+ } else {
+ cpu_dev->of_node = np;
+ ret = of_init_opp_table(cpu_dev);
+ }
+ of_node_put(np);
+ of_node_put(parent);
+
+ return ret;
}
return -ENODEV;
@@ -54,15 +60,24 @@ static int dt_init_opp_table(struct device *cpu_dev)
static int dt_get_transition_latency(struct device *cpu_dev)
{
- struct device_node *np = NULL;
+ struct device_node *np, *parent;
u32 transition_latency = CPUFREQ_ETERNAL;
int count = 0;
- for_each_child_of_node(of_find_node_by_path("/cpus"), np) {
+ parent = of_find_node_by_path("/cpus");
+ if (!parent) {
+ pr_err("failed to find OF /cpus\n");
+ return -ENOENT;
+ }
+
+ for_each_child_of_node(parent, np) {
if (count++ != cpu_dev->id)
continue;
of_property_read_u32(np, "clock-latency", &transition_latency);
+ of_node_put(np);
+ of_node_put(parent);
+
return 0;
}
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