There's one corner case need to be fixed: !cpuidle_ops[cpu].init.
patch1 tries to address this corner case.
patch2 tries to improve arm_cpuidle_suspend() a bit by moving .suspend
check into arm_cpuidle_read_ops().
Since v2:
- add back patch1.
Since v1:
- drop patch1, I.E "ARM: cpuidle: fix !cpuidle_ops[cpu].init case
during init", because there may be platforms which doesn't need the
init member at all.
- adopt Daniel's suggestion to move the cpuidle_ops.suspend check to
arm_cpuidle_read_ops().
Jisheng Zhang (2):
ARM: cpuidle: fix !cpuidle_ops[cpu].init case during init
ARM: cpuidle: make arm_cpuidle_suspend() a bit more efficient
arch/arm/kernel/cpuidle.c | 23 +++++++++++++----------
1 file changed, 13 insertions(+), 10 deletions(-)
--
2.8.0.rc3
Currently, we check cpuidle_ops.suspend every time when entering a
low-power idle state. But this check could be avoided in this hot path
by moving it into arm_cpuidle_read_ops() to reduce arm_cpuidle_suspend
overhead a bit.
Signed-off-by: Jisheng Zhang <[email protected]>
---
arch/arm/kernel/cpuidle.c | 17 ++++++-----------
1 file changed, 6 insertions(+), 11 deletions(-)
diff --git a/arch/arm/kernel/cpuidle.c b/arch/arm/kernel/cpuidle.c
index 18b5a73..c4280e3 100644
--- a/arch/arm/kernel/cpuidle.c
+++ b/arch/arm/kernel/cpuidle.c
@@ -47,18 +47,13 @@ int arm_cpuidle_simple_enter(struct cpuidle_device *dev,
* This function calls the underlying arch specific low level PM code as
* registered at the init time.
*
- * Returns -EOPNOTSUPP if no suspend callback is defined, the result of the
- * callback otherwise.
+ * Returns the result of the suspend callback.
*/
int arm_cpuidle_suspend(int index)
{
- int ret = -EOPNOTSUPP;
int cpu = smp_processor_id();
- if (cpuidle_ops[cpu].suspend)
- ret = cpuidle_ops[cpu].suspend(index);
-
- return ret;
+ return cpuidle_ops[cpu].suspend(index);
}
/**
@@ -92,8 +87,8 @@ static struct cpuidle_ops *__init arm_cpuidle_get_ops(const char *method)
* process.
*
* Return 0 on sucess, -ENOENT if no 'enable-method' is defined, -EOPNOTSUPP if
- * no cpuidle_ops is registered for the 'enable-method', or if no init callback
- * is defined.
+ * no cpuidle_ops is registered for the 'enable-method', or if either init or
+ * suspend callback isn't defined.
*/
static int __init arm_cpuidle_read_ops(struct device_node *dn, int cpu)
{
@@ -111,8 +106,8 @@ static int __init arm_cpuidle_read_ops(struct device_node *dn, int cpu)
return -EOPNOTSUPP;
}
- if (!ops->init) {
- pr_warn("cpuidle_ops '%s': no init callback\n",
+ if (!ops->init || !ops->suspend) {
+ pr_warn("cpuidle_ops '%s': no init or suspend callback\n",
enable_method);
return -EOPNOTSUPP;
}
--
2.8.0.rc3
Let's assume cpuidle_ops exists but it doesn't implement the according
init callback, current arm_cpuidle_init() will return success to its
caller, but in fact it should return -EOPNOTSUPP.
Signed-off-by: Jisheng Zhang <[email protected]>
---
arch/arm/kernel/cpuidle.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/arch/arm/kernel/cpuidle.c b/arch/arm/kernel/cpuidle.c
index 703926e..18b5a73 100644
--- a/arch/arm/kernel/cpuidle.c
+++ b/arch/arm/kernel/cpuidle.c
@@ -92,7 +92,8 @@ static struct cpuidle_ops *__init arm_cpuidle_get_ops(const char *method)
* process.
*
* Return 0 on sucess, -ENOENT if no 'enable-method' is defined, -EOPNOTSUPP if
- * no cpuidle_ops is registered for the 'enable-method'.
+ * no cpuidle_ops is registered for the 'enable-method', or if no init callback
+ * is defined.
*/
static int __init arm_cpuidle_read_ops(struct device_node *dn, int cpu)
{
@@ -110,6 +111,12 @@ static int __init arm_cpuidle_read_ops(struct device_node *dn, int cpu)
return -EOPNOTSUPP;
}
+ if (!ops->init) {
+ pr_warn("cpuidle_ops '%s': no init callback\n",
+ enable_method);
+ return -EOPNOTSUPP;
+ }
+
cpuidle_ops[cpu] = *ops; /* structure copy */
pr_notice("cpuidle: enable-method property '%s'"
@@ -129,7 +136,8 @@ static int __init arm_cpuidle_read_ops(struct device_node *dn, int cpu)
* Returns:
* 0 on success,
* -ENODEV if it fails to find the cpu node in the device tree,
- * -EOPNOTSUPP if it does not find a registered cpuidle_ops for this cpu,
+ * -EOPNOTSUPP if it does not find a registered and valid cpuidle_ops for
+ * this cpu,
* -ENOENT if it fails to find an 'enable-method' property,
* -ENXIO if the HW reports a failure or a misconfiguration,
* -ENOMEM if the HW report an memory allocation failure
@@ -143,7 +151,7 @@ int __init arm_cpuidle_init(int cpu)
return -ENODEV;
ret = arm_cpuidle_read_ops(cpu_node, cpu);
- if (!ret && cpuidle_ops[cpu].init)
+ if (!ret)
ret = cpuidle_ops[cpu].init(cpu_node, cpu);
of_node_put(cpu_node);
--
2.8.0.rc3