From 4e695c71f384791ef27489198681a68e265f4a2c Mon Sep 17 00:00:00 2001
From: DipSwitch <dipswitch@ownage4u.nl>
Date: Wed, 31 May 2017 14:06:23 +0200
Subject: [PATCH] driver/at86rf2xx: Fix possible race condition where
 at86rf2xx_configure returns to the wrong state if waited on finished state in
 at86rf2xx_setstate

---
 drivers/at86rf2xx/at86rf2xx_getset.c   | 18 ++++++++++--------
 drivers/at86rf2xx/at86rf2xx_internal.c |  4 ++--
 drivers/include/at86rf2xx.h            |  4 +++-
 3 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/drivers/at86rf2xx/at86rf2xx_getset.c b/drivers/at86rf2xx/at86rf2xx_getset.c
index 8f5265095ebe5..b61d950bdb78f 100644
--- a/drivers/at86rf2xx/at86rf2xx_getset.c
+++ b/drivers/at86rf2xx/at86rf2xx_getset.c
@@ -444,17 +444,12 @@ static inline void _set_state(at86rf2xx_t *dev, uint8_t state, uint8_t cmd)
     dev->state = state;
 }
 
-void at86rf2xx_set_state(at86rf2xx_t *dev, uint8_t state)
+uint8_t at86rf2xx_set_state(at86rf2xx_t *dev, uint8_t state)
 {
     uint8_t old_state = at86rf2xx_get_status(dev);
 
     if (state == old_state) {
-        return;
-    }
-
-    if (state == AT86RF2XX_STATE_FORCE_TRX_OFF) {
-        _set_state(dev, AT86RF2XX_STATE_TRX_OFF, state);
-        return;
+        return old_state;
     }
 
     /* make sure there is no ongoing transmission, or state transition already
@@ -465,8 +460,13 @@ void at86rf2xx_set_state(at86rf2xx_t *dev, uint8_t state)
         old_state = at86rf2xx_get_status(dev);
     }
 
+    if (state == AT86RF2XX_STATE_FORCE_TRX_OFF) {
+        _set_state(dev, AT86RF2XX_STATE_TRX_OFF, state);
+        return old_state;
+    }
+
     if (state == old_state) {
-        return;
+        return old_state;
     }
 
     /* we need to go via PLL_ON if we are moving between RX_AACK_ON <-> TX_ARET_ON */
@@ -493,6 +493,8 @@ void at86rf2xx_set_state(at86rf2xx_t *dev, uint8_t state)
     } else {
         _set_state(dev, state, state);
     }
+
+    return old_state;
 }
 
 void at86rf2xx_reset_state_machine(at86rf2xx_t *dev)
diff --git a/drivers/at86rf2xx/at86rf2xx_internal.c b/drivers/at86rf2xx/at86rf2xx_internal.c
index 660b691b6cfc1..6a2017d0f8a61 100644
--- a/drivers/at86rf2xx/at86rf2xx_internal.c
+++ b/drivers/at86rf2xx/at86rf2xx_internal.c
@@ -147,7 +147,7 @@ void at86rf2xx_hardware_reset(at86rf2xx_t *dev)
 
 void at86rf2xx_configure_phy(at86rf2xx_t *dev)
 {
-    uint8_t state = at86rf2xx_get_status(dev);
+    uint8_t prev_state = at86rf2xx_get_status(dev);
 
     /* we must be in TRX_OFF before changing the PHY configuration */
     at86rf2xx_set_state(dev, AT86RF2XX_STATE_TRX_OFF);
@@ -200,7 +200,7 @@ void at86rf2xx_configure_phy(at86rf2xx_t *dev)
 #endif
 
     /* Return to the state we had before reconfiguring */
-    at86rf2xx_set_state(dev, state);
+    at86rf2xx_set_state(dev, prev_state);
 }
 
 #if defined(MODULE_AT86RF233) || defined(MODULE_AT86RF231)
diff --git a/drivers/include/at86rf2xx.h b/drivers/include/at86rf2xx.h
index 3afee08987fcc..9e3453f2d807e 100644
--- a/drivers/include/at86rf2xx.h
+++ b/drivers/include/at86rf2xx.h
@@ -385,8 +385,10 @@ void at86rf2xx_set_option(at86rf2xx_t *dev, uint16_t option, bool state);
  *
  * @param[in] dev           device to change state of
  * @param[in] state         the targeted new state
+ *
+ * @return                  the previous error before the new state was set
  */
-void at86rf2xx_set_state(at86rf2xx_t *dev, uint8_t state);
+uint8_t at86rf2xx_set_state(at86rf2xx_t *dev, uint8_t state);
 
 /**
  * @brief   Reset the internal state machine to TRX_OFF mode.