power: return error when environment already set

On attempt to set_env in already initialized state notify
user by returning error that operation cannot be performed.

Signed-off-by: Marcin Hajkowski <marcinx.hajkowski@intel.com>
Acked-by: Anatoly Burakov <anatoly.burakov@intel.com>

diff --git a/lib/librte_power/rte_power.c b/lib/librte_power/rte_power.c
index 540d69b..ed70108 100644 (file)
--- a/lib/librte_power/rte_power.c
+++ b/lib/librte_power/rte_power.c
@@ -33,8 +33,9 @@ rte_power_set_env(enum power_management_env env)
        rte_spinlock_lock(&global_env_cfg_lock);
 
        if (global_default_env != PM_ENV_NOT_SET) {
+               RTE_LOG(ERR, POWER, "Power Management Environment already set.\n");
                rte_spinlock_unlock(&global_env_cfg_lock);
-               return 0;
+               return -1;
        }
 
        int ret = 0;

diff --git a/lib/librte_power/rte_power.h b/lib/librte_power/rte_power.h
index 47db69f..0650112 100644 (file)
--- a/lib/librte_power/rte_power.h
+++ b/lib/librte_power/rte_power.h
@@ -26,7 +26,8 @@ enum power_management_env {PM_ENV_NOT_SET, PM_ENV_ACPI_CPUFREQ, PM_ENV_KVM_VM,
 /**
  * Set the default power management implementation. If this is not called prior
  * to rte_power_init(), then auto-detect of the environment will take place.
- * It is thread safe.
+ * It is thread safe. New env can be set only in unitialized state
+ * (thus rte_power_unset_env must be called if different env was already set).
  *
  * @param env
  *  env. The environment in which to initialise Power Management for.