cpuidle/powernv: cleanup cpuidle-powernv.c

- Use stack instead of kzalloc'ed memory for variables while probing
   device tree for idle states.
 - Set cap for number of idle states that can be added to
   cpuidle_state_table
 - Minor change in way we check of_property_read_u32_array for error
   for sake of consistency
 - Drop unnecessary "&" while assigning function pointer

Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: linux-pm@vger.kernel.org
Signed-off-by: Shreyas B. Prabhu <shreyas@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/drivers/cpuidle/cpuidle-powernv.c b/drivers/cpuidle/cpuidle-powernv.c
index 3a763a8..600bbe1 100644 (file)
--- a/drivers/cpuidle/cpuidle-powernv.c
+++ b/drivers/cpuidle/cpuidle-powernv.c
@@ -100,7 +100,7 @@ static struct cpuidle_state powernv_states[CPUIDLE_STATE_MAX] = {
                .desc = "snooze",
                .exit_latency = 0,
                .target_residency = 0,
-               .enter = &snooze_loop },
+               .enter = snooze_loop },
 };
 
 static int powernv_cpuidle_add_cpu_notifier(struct notifier_block *n,
@@ -166,7 +166,9 @@ static int powernv_add_idle_states(void)
        struct device_node *power_mgt;
        int nr_idle_states = 1; /* Snooze */
        int dt_idle_states;
-       u32 *latency_ns, *residency_ns, *flags;
+       u32 latency_ns[CPUIDLE_STATE_MAX];
+       u32 residency_ns[CPUIDLE_STATE_MAX];
+       u32 flags[CPUIDLE_STATE_MAX];
        int i, rc;
 
        /* Currently we have snooze statically defined */
@@ -184,22 +186,28 @@ static int powernv_add_idle_states(void)
                goto out;
        }
 
-       flags = kzalloc(sizeof(*flags) * dt_idle_states, GFP_KERNEL);
+       /*
+        * Since snooze is used as first idle state, max idle states allowed is
+        * CPUIDLE_STATE_MAX -1
+        */
+       if (dt_idle_states > CPUIDLE_STATE_MAX - 1) {
+               pr_warn("cpuidle-powernv: discovered idle states more than allowed");
+               dt_idle_states = CPUIDLE_STATE_MAX - 1;
+       }
+
        if (of_property_read_u32_array(power_mgt,
                        "ibm,cpu-idle-state-flags", flags, dt_idle_states)) {
                pr_warn("cpuidle-powernv : missing ibm,cpu-idle-state-flags in DT\n");
-               goto out_free_flags;
+               goto out;
        }
 
-       latency_ns = kzalloc(sizeof(*latency_ns) * dt_idle_states, GFP_KERNEL);
-       rc = of_property_read_u32_array(power_mgt,
-               "ibm,cpu-idle-state-latencies-ns", latency_ns, dt_idle_states);
-       if (rc) {
+       if (of_property_read_u32_array(power_mgt,
+               "ibm,cpu-idle-state-latencies-ns", latency_ns,
+               dt_idle_states)) {
                pr_warn("cpuidle-powernv: missing ibm,cpu-idle-state-latencies-ns in DT\n");
-               goto out_free_latency;
+               goto out;
        }
 
-       residency_ns = kzalloc(sizeof(*residency_ns) * dt_idle_states, GFP_KERNEL);
        rc = of_property_read_u32_array(power_mgt,
                "ibm,cpu-idle-state-residency-ns", residency_ns, dt_idle_states);
 
@@ -215,7 +223,7 @@ static int powernv_add_idle_states(void)
                        strcpy(powernv_states[nr_idle_states].desc, "Nap");
                        powernv_states[nr_idle_states].flags = 0;
                        powernv_states[nr_idle_states].target_residency = 100;
-                       powernv_states[nr_idle_states].enter = &nap_loop;
+                       powernv_states[nr_idle_states].enter = nap_loop;
                }
 
                /*
@@ -230,7 +238,7 @@ static int powernv_add_idle_states(void)
                        strcpy(powernv_states[nr_idle_states].desc, "FastSleep");
                        powernv_states[nr_idle_states].flags = CPUIDLE_FLAG_TIMER_STOP;
                        powernv_states[nr_idle_states].target_residency = 300000;
-                       powernv_states[nr_idle_states].enter = &fastsleep_loop;
+                       powernv_states[nr_idle_states].enter = fastsleep_loop;
                }
 #endif
                powernv_states[nr_idle_states].exit_latency =
@@ -243,12 +251,6 @@ static int powernv_add_idle_states(void)
 
                nr_idle_states++;
        }
-
-       kfree(residency_ns);
-out_free_latency:
-       kfree(latency_ns);
-out_free_flags:
-       kfree(flags);
 out:
        return nr_idle_states;
 }