[dpdk-dev] [PATCH v2 2/4] power: return error in set env when power env already set

[Hajkowski <marcinx.hajkowski@intel.com>]

From: Marcin Hajkowski <marcinx.hajkowski@intel.com>

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>
---
 doc/guides/rel_notes/release_19_05.rst | 4 ++++
 lib/librte_power/rte_power.c           | 3 ++-
 lib/librte_power/rte_power.h           | 3 ++-
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/doc/guides/rel_notes/release_19_05.rst b/doc/guides/rel_notes/release_19_05.rst
index 65371e4c8..0da26b937 100644
--- a/doc/guides/rel_notes/release_19_05.rst
+++ b/doc/guides/rel_notes/release_19_05.rst
@@ -120,9 +120,13 @@ API Changes
    Also, make sure to start the actual text at the margin.
    =========================================================
 
+
    * power: ``rte_power_set_env`` and ``rte_power_unset_env`` functions
      have been modified to be thread safe.
 
+   * power: Function ``rte_power_set_env`` modified to return -1 if environment
+     has been already set.
+
 ABI Changes
 -----------
 
diff --git a/lib/librte_power/rte_power.c b/lib/librte_power/rte_power.c
index 540d69be7..ed701087d 100644
--- 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 54b76b4ee..a3130e709 100644
--- 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.
-- 
2.17.2