cpuidle: Make cpuidle_enable_device() call poll_idle_init()

The following scenario is possible with the current cpuidle code and
the ACPI cpuidle driver:
(1) acpi_processor_cst_has_changed() is called,
(2) cpuidle_disable_device() is called,
(3) cpuidle_remove_state_sysfs() is called to remove the (presumably
    outdated) states info from sysfs,
(3) acpi_processor_get_power_info() is called, the first entry in the
    pr->power.states[] table is filled with zeros,
(4) acpi_processor_setup_cpuidle() is called and it doesn't fill the
    first entry in pr->power.states[],
(5) cpuidle_enable_device() is called,
(6) __cpuidle_register_device() is _not_ called, since the device has
    already been registered,
(7) Consequently, poll_idle_init() is _not_ called either,
(8) cpuidle_add_state_sysfs() is called to create the sysfs attributes
    for the new states and it uses the bogus first table entry from
    acpi_processor_get_power_info() for creating state0.

This problem is avoided if cpuidle_enable_device()
unconditionally calls poll_idle_init().

Reported-by: Len Brown <len.brown@intel.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Len Brown <len.brown@intel.com>
cc: stable@kernel.org

1 files changed, 41 insertions, 41 deletions

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index a50710843378..97df791c74cb 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -154,6 +154,45 @@ void cpuidle_resume_and_unlock(void)
 
 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
 
+#ifdef CONFIG_ARCH_HAS_CPU_RELAX
+static int poll_idle(struct cpuidle_device *dev, struct cpuidle_state *st)
+{
+        ktime_t t1, t2;
+        s64 diff;
+        int ret;
+
+        t1 = ktime_get();
+        local_irq_enable();
+        while (!need_resched())
+                cpu_relax();
+
+        t2 = ktime_get();
+        diff = ktime_to_us(ktime_sub(t2, t1));
+        if (diff > INT_MAX)
+                diff = INT_MAX;
+
+        ret = (int) diff;
+        return ret;
+}
+
+static void poll_idle_init(struct cpuidle_device *dev)
+{
+        struct cpuidle_state *state = &dev->states[0];
+
+        cpuidle_set_statedata(state, NULL);
+
+        snprintf(state->name, CPUIDLE_NAME_LEN, "C0");
+        snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
+        state->exit_latency = 0;
+        state->target_residency = 0;
+        state->power_usage = -1;
+        state->flags = CPUIDLE_FLAG_POLL;
+        state->enter = poll_idle;
+}
+#else
+static void poll_idle_init(struct cpuidle_device *dev) {}
+#endif /* CONFIG_ARCH_HAS_CPU_RELAX */
+
 /**
  * cpuidle_enable_device - enables idle PM for a CPU
  * @dev: the CPU
@@ -178,6 +217,8 @@ int cpuidle_enable_device(struct cpuidle_device *dev)
                         return ret;
         }
 
+        poll_idle_init(dev);
+
         if ((ret = cpuidle_add_state_sysfs(dev)))
                 return ret;
 
@@ -232,45 +273,6 @@ void cpuidle_disable_device(struct cpuidle_device *dev)
 
 EXPORT_SYMBOL_GPL(cpuidle_disable_device);
 
-#ifdef CONFIG_ARCH_HAS_CPU_RELAX
-static int poll_idle(struct cpuidle_device *dev, struct cpuidle_state *st)
-{
-        ktime_t t1, t2;
-        s64 diff;
-        int ret;
-
-        t1 = ktime_get();
-        local_irq_enable();
-        while (!need_resched())
-                cpu_relax();
-
-        t2 = ktime_get();
-        diff = ktime_to_us(ktime_sub(t2, t1));
-        if (diff > INT_MAX)
-                diff = INT_MAX;
-
-        ret = (int) diff;
-        return ret;
-}
-
-static void poll_idle_init(struct cpuidle_device *dev)
-{
-        struct cpuidle_state *state = &dev->states[0];
-
-        cpuidle_set_statedata(state, NULL);
-
-        snprintf(state->name, CPUIDLE_NAME_LEN, "C0");
-        snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
-        state->exit_latency = 0;
-        state->target_residency = 0;
-        state->power_usage = -1;
-        state->flags = CPUIDLE_FLAG_POLL;
-        state->enter = poll_idle;
-}
-#else
-static void poll_idle_init(struct cpuidle_device *dev) {}
-#endif /* CONFIG_ARCH_HAS_CPU_RELAX */
-
 /**
  * __cpuidle_register_device - internal register function called before register
  * and enable routines
@@ -291,8 +293,6 @@ static int __cpuidle_register_device(struct cpuidle_device *dev)
 
         init_completion(&dev->kobj_unregister);
 
-        poll_idle_init(dev);
-
         /*
          * cpuidle driver should set the dev->power_specified bit
          * before registering the device if the driver provides