[LIBDCE] Replace Semaphore with Mutex

This patch reverts the below commit:
"abd5152ca071e552954571862635666297221177
[LIBDCE] Mutual exclusion of Engine_open and Engine_close"
Description:
-----------
(1) The current semaphore logic doesn't protect the engine open/close
calls across processes. It is confirmed on QNX that two instances of
dce test app is creating two different instances of semaphore.
Hence, other than the delay the current semaphore doesn't add
any protection for the mutli process <-> multi instance scenarios.
(2) For the single process <-> multi instance scenario, it does protect
the engine open/close calls, but it fails due to lack of reference counting
And also, it is not sure why we need to protect the entire engine_open/close.
Hence the current semaphore is replaced with mutex to protect the ipc handle
create/close.

Change-Id: Ibdad089bdd39cd5afc813373e84bf91fa8920860
Signed-off-by: Sunita Nadampalli <sunitan@ti.com>

2 files changed, 20 insertions, 74 deletions

diff --git a/libdce.c b/libdce.c
index 06844cc..deebc94 100644
--- a/libdce.c
+++ b/libdce.c
@@ -33,10 +33,8 @@
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
+#include <pthread.h>
 #include <errno.h>
-#include <fcntl.h>        /* For O_* constants */
-#include <sys/stat.h>     /* For mode constants */
-#include <semaphore.h>
 
 /* IPC Headers */
 #include <MmRpc.h>
@@ -51,8 +49,8 @@
 /********************* GLOBALS ***********************/
 /* Hande used for Remote Communication                               */
 MmRpc_Handle    MmRpcHandle = NULL;
-sem_t          *dce_semaphore = NULL;
-static int      count = 0;
+static pthread_mutex_t    mutex = PTHREAD_MUTEX_INITIALIZER;
+static int      __ClientCount = 0;
 int             dce_debug = DCE_DEBUG_LEVEL;
 
 /****************** INLINE FUNCTIONS ********************/
@@ -112,55 +110,6 @@ void dce_free(void *ptr)
     memplugin_free(ptr);
 }
 
-static inline int dce_sem_init(sem_t * *sem)
-{
-    if( *sem ) {
-        return (DCE_EOK);
-    }
-
-#ifdef BUILDOS_ANDROID
-    *sem = malloc(sizeof(sem_t));
-    int    ret = sem_init(*sem, 0, 1);
-    return (ret);
-#else
-    *sem = sem_open("/dce_semaphore", O_CREAT, S_IRWXU | S_IRWXO | S_IRWXG, 1);
-    return ((*sem) ? DCE_EOK : SEM_FAILED);
-#endif
-}
-
-static inline int dce_sem_wait(sem_t *sem)
-{
-    if( NULL == sem ) {
-        return (DCE_EINVALID_INPUT);
-    }
-
-    return (sem_wait(sem));
-}
-
-static inline int dce_sem_post(sem_t *sem)
-{
-    if( NULL == sem ) {
-        return (DCE_EINVALID_INPUT);
-    }
-
-    return (sem_post(sem));
-}
-
-static inline void dce_sem_close(sem_t * *sem)
-{
-    if( NULL == *sem ) {
-        return;
-    }
-
-#ifdef BUILDOS_ANDROID
-    sem_destroy(*sem);
-    free(*sem);
-#else
-    sem_close(*sem);
-#endif
-    *sem = NULL;
-}
-
 /*=====================================================================================*/
 /** dce_ipc_init            : Initialize MmRpc. This function is called within Engine_open().
  *
@@ -173,16 +122,18 @@ static int dce_ipc_init(void)
 
     DEBUG(" >> dce_ipc_init\n");
 
-    count++;
+    __ClientCount++;
     /* Check if already Initialized */
-    _ASSERT(count == 1, DCE_EOK);
+    if (__ClientCount > 1) {
+        goto EXIT;
+    }
 
     /* Create remote server insance */
     MmRpc_Params_init(&args);
 
     eError = MmRpc_create(DCE_DEVICE_NAME, &args, &MmRpcHandle);
 
-    _ASSERT_AND_EXECUTE(eError == DCE_EOK, DCE_EIPC_CREATE_FAIL, count--);
+    _ASSERT_AND_EXECUTE(eError == DCE_EOK, DCE_EIPC_CREATE_FAIL, __ClientCount--);
 
     DEBUG("open(/dev/" DCE_DEVICE_NAME ") -> 0x%x\n", (int)MmRpcHandle);
 
@@ -196,8 +147,8 @@ EXIT:
  */
 static void dce_ipc_deinit()
 {
-    count--;
-    if( count > 0 ) {
+    __ClientCount--;
+    if( __ClientCount > 0 ) {
         goto EXIT;
     }
 
@@ -229,12 +180,10 @@ Engine_Handle Engine_open(String name, Engine_Attrs *attrs, Engine_Error *ec)
 
     _ASSERT(name != '\0', DCE_EINVALID_INPUT);
 
-    _ASSERT(dce_sem_init(&dce_semaphore) == DCE_EOK, DCE_ESEMAPHORE_FAIL);
-    /* Lock dce_ipc_init() and Engine_open() IPU call to prevent hang*/
-    _ASSERT(dce_sem_wait(dce_semaphore) == DCE_EOK, DCE_ESEMAPHORE_FAIL);
+    pthread_mutex_lock(&mutex);
 
     /* Initialize IPC. In case of Error Deinitialize them */
-    _ASSERT_AND_EXECUTE(dce_ipc_init() == DCE_EOK, DCE_EIPC_CREATE_FAIL, dce_sem_close(&dce_semaphore));
+    _ASSERT(dce_ipc_init() == DCE_EOK, DCE_EIPC_CREATE_FAIL);
 
     INFO(">> Engine_open Params::name = %s size = %d\n", name, strlen(name));
     /* Allocate Shared memory for the engine_open rpc msg structure*/
@@ -266,15 +215,15 @@ Engine_Handle Engine_open(String name, Engine_Attrs *attrs, Engine_Error *ec)
     if( ec ) {
         *ec = engine_open_msg->error_code;
     }
-
 EXIT:
-    /* Unlock dce_ipc_init() and Engine_open() IPU call */
-    _ASSERT(dce_sem_post(dce_semaphore) == DCE_EOK, DCE_ESEMAPHORE_FAIL);
 
     memplugin_free(engine_open_msg);
+
     if( engine_attrs ) {
         memplugin_free(engine_attrs);
     }
+    pthread_mutex_unlock(&mutex);
+
     return ((Engine_Handle)engine_handle);
 }
 
@@ -289,10 +238,9 @@ Void Engine_close(Engine_Handle engine)
     int32_t             fxnRet;
     dce_error_status    eError = DCE_EOK;
 
-    _ASSERT(engine != NULL, DCE_EINVALID_INPUT);
+    pthread_mutex_lock(&mutex);
 
-    /* Lock dce_ipc_deinit() and Engine_close() IPU call */
-    _ASSERT(dce_sem_wait(dce_semaphore) == DCE_EOK, DCE_ESEMAPHORE_FAIL);
+    _ASSERT(engine != NULL, DCE_EINVALID_INPUT);
 
     /* Marshall function arguments into the send buffer */
     Fill_MmRpc_fxnCtx(&fxnCtx, DCE_RPC_ENGINE_CLOSE, 1, 0, NULL);
@@ -306,9 +254,8 @@ Void Engine_close(Engine_Handle engine)
 EXIT:
     dce_ipc_deinit();
 
-    /* Unlock dce_ipc_deinit() and Engine_close() IPU call */
-    _ASSERT(dce_sem_post(dce_semaphore) == DCE_EOK, DCE_ESEMAPHORE_FAIL);
-    dce_sem_close(&dce_semaphore);
+    pthread_mutex_unlock(&mutex);
+
     return;
 }
 
diff --git a/libdce.h b/libdce.h
index ea63e66..9377892 100644
--- a/libdce.h
+++ b/libdce.h
@@ -54,8 +54,7 @@ typedef enum dce_error_status {
     DCE_EIPC_CREATE_FAIL = -4,
     DCE_EIPC_CALL_FAIL = -5,
     DCE_EINVALID_INPUT = -6,
-    DCE_EOMAPDRM_FAIL = -7,
-    DCE_ESEMAPHORE_FAIL = -8
+    DCE_EOMAPDRM_FAIL = -7
 } dce_error_status;
 
 /***************************** Memory Allocation/Free APIs *****************************/