From 67d28bec545857b329f76ffe3cc9b98dbac7ce69 Mon Sep 17 00:00:00 2001
From: Martin Troxler <martin.troxler@komaxgroup.com>
Date: Thu, 6 Jan 2011 13:11:21 +0100
Subject: [PATCH] always use rt_mutex instead of semaphore for mutual exclusion
 on kernels >= 2.6.24 (removed --enable-mutex build option)

---
 configure.ac     | 24 ------------------------
 master/globals.h | 11 ++++++-----
 2 files changed, 6 insertions(+), 29 deletions(-)

diff --git a/configure.ac b/configure.ac
index cd85a55a..387f4db0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -536,30 +536,6 @@ if test "x${regalias}" = "x1"; then
     AC_DEFINE([EC_REGALIAS], [1], [Read alias adresses from register])
 fi
 
-#------------------------------------------------------------------------------
-# use mutexes instead of semaphores
-#------------------------------------------------------------------------------
-
-AC_ARG_ENABLE([mutex],
-    AS_HELP_STRING([--enable-mutex],
-                   [Use mutex instead of semaphores for mutual exclusion (default: no)]),
-    [
-        case "${enableval}" in
-            yes) mutex=1
-                ;;
-            no) mutex=0
-                ;;
-            *) AC_MSG_ERROR([Invalid value for --enable-mutex])
-                ;;
-        esac
-    ],
-    [mutex=0]
-)
-
-if test "x${mutex}" = "x1"; then
-    AC_DEFINE([EC_USE_MUTEX], [1], [Use mutex for mutual exclusion])
-fi
-
 
 #------------------------------------------------------------------------------
 # Command-line tool
diff --git a/master/globals.h b/master/globals.h
index 859eee94..d2c135df 100644
--- a/master/globals.h
+++ b/master/globals.h
@@ -40,9 +40,10 @@
 #include "../include/ecrt.h"
 
 #ifdef __KERNEL__
-#ifdef EC_USE_MUTEX
+#include <linux/version.h>
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,24)
 #include <linux/rtmutex.h>
-#endif  // EC_USE_MUTEX
+#endif  // KERNEL_VERSION(2,6,24)
 #endif // __KERNEL__
 
 /******************************************************************************
@@ -318,7 +319,7 @@ typedef struct ec_slave ec_slave_t; /**< \see ec_slave. */
 /** Mutual exclusion helpers.
  *
  */
-#ifdef EC_USE_MUTEX
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,24)
 #define ec_mutex_t rt_mutex
 static inline void ec_mutex_init(struct ec_mutex_t *mutex)
 {
@@ -340,7 +341,7 @@ static inline void ec_mutex_unlock(struct ec_mutex_t *mutex)
 {
     rt_mutex_unlock(mutex);
 }
-#else   // EC_USE_MUTEX
+#else   // < KERNEL_VERSION(2,6,24)
 #define ec_mutex_t semaphore
 static inline void ec_mutex_init(struct ec_mutex_t *sem)
 {
@@ -364,7 +365,7 @@ static inline void ec_mutex_unlock(struct ec_mutex_t *sem)
     up(sem);
 }
 
-#endif // EC_USE_MUTEX
+#endif // KERNEL_VERSION(2,6,24)
 #endif // __KERNEL__
 
 #endif