Changeset 15d9fe6 in mainline for kernel/generic/src/synch/mutex.c

Timestamp:

2017-10-28T11:26:43Z (6 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

c1f68b0

Parents:

7cf8522

Message:

Implement recursive mutex

File:

• kernel/generic/src/synch/mutex.c (modified) (5 diffs)

kernel/generic/src/synch/mutex.c

@@ -46 +46 @@
 /** Initialize mutex.
  *
- * @param mtx  Mutex.
- * @param type Type of the mutex.
+ * @param mtx   Mutex.
+ * @param type  Type of the mutex.
  */
 void mutex_initialize(mutex_t *mtx, mutex_type_t type)
 {
         mtx->type = type;
+        mtx->owner = NULL;
+        mtx->nesting = 0;
         semaphore_initialize(&mtx->sem, 1);
 }
@@ -57 +59 @@
 /** Find out whether the mutex is currently locked.
  *
- * @param mtx           Mutex.
- * @return              True if the mutex is locked, false otherwise.
+ * @param mtx  Mutex.
+ *
+ * @return  True if the mutex is locked, false otherwise.
  */
 bool mutex_locked(mutex_t *mtx)
@@ -71 +74 @@
  * Timeout mode and non-blocking mode can be requested.
  *
- * @param mtx   Mutex.
- * @param usec  Timeout in microseconds.
- * @param flags Specify mode of operation.
+ * @param mtx    Mutex.
+ * @param usec   Timeout in microseconds.
+ * @param flags  Specify mode of operation.
  *
- * For exact description of possible combinations of
- * usec and flags, see comment for waitq_sleep_timeout().
+ * For exact description of possible combinations of usec and flags, see
+ * comment for waitq_sleep_timeout().
  *
  * @return See comment for waitq_sleep_timeout().
@@ -85 +88 @@
         int rc;
 
-        if ((mtx->type == MUTEX_PASSIVE) && (THREAD)) {
+        if (mtx->type == MUTEX_PASSIVE && THREAD) {
                 rc = _semaphore_down_timeout(&mtx->sem, usec, flags);
+        } else if (mtx->type == MUTEX_RECURSIVE) {
+                assert(THREAD);
+
+                if (mtx->owner == THREAD) {
+                        mtx->nesting++;
+                        return ESYNCH_OK_ATOMIC;
+                } else {
+                        rc = _semaphore_down_timeout(&mtx->sem, usec, flags);
+                        if (SYNCH_OK(rc)) {
+                                mtx->owner = THREAD;
+                                mtx->nesting = 1;
+                        }
+                }
         } else {
-                assert((mtx->type == MUTEX_ACTIVE) || (!THREAD));
+                assert((mtx->type == MUTEX_ACTIVE) || !THREAD);
                 assert(usec == SYNCH_NO_TIMEOUT);
                 assert(!(flags & SYNCH_FLAGS_INTERRUPTIBLE));
@@ -114 +130 @@
 /** Release mutex.
  *
- * @param mtx Mutex.
+ * @param mtx  Mutex.
  */
 void mutex_unlock(mutex_t *mtx)
 {
+        if (mtx->type == MUTEX_RECURSIVE) {
+                assert(mtx->owner == THREAD);
+                if (--mtx->nesting > 0)
+                        return;
+                mtx->owner = NULL;
+        }
         semaphore_up(&mtx->sem);
 }