Changeset 08a19ba in mainline for kernel/generic/src/synch/mutex.c

Timestamp:

2008-06-23T18:44:48Z (15 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

lfn, master, serial

Children:

1a1744e

Parents:

deaf8d5

Message:

Support for active mutexes. Active mutexes implement busy waiting, pretty much
in the same way as spinlocks, but can be passed to condition variables, which is
the motivation for this enhancement.

File:

• kernel/generic/src/synch/mutex.c (modified) (1 diff)

kernel/generic/src/synch/mutex.c

@@ -39 +39 @@
 #include <synch/semaphore.h>
 #include <synch/synch.h>
+#include <debug.h>
 
-/** Initialize mutex
+/** Initialize mutex.
  *
- * Initialize mutex.
- *
- * @param mtx Mutex.
+ * @param mtx           Mutex.
+ * @param type          Type of the mutex.
  */
-void mutex_initialize(mutex_t *mtx)
+void mutex_initialize(mutex_t *mtx, mutex_type_t type)
 {
+        mtx->type = type;
         semaphore_initialize(&mtx->sem, 1);
 }
 
-/** Acquire mutex
+/** Acquire mutex.
  *
- * Acquire mutex.
  * 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().
  *
- * @return See comment for waitq_sleep_timeout().
+ * @return              See comment for waitq_sleep_timeout().
  */
 int _mutex_lock_timeout(mutex_t *mtx, uint32_t usec, int flags)
 {
-        return _semaphore_down_timeout(&mtx->sem, usec, flags);
+        int rc;
+
+        if (mtx->type == MUTEX_PASSIVE) {
+                rc = _semaphore_down_timeout(&mtx->sem, usec, flags);
+        } else {
+                ASSERT(mtx->type == MUTEX_ACTIVE);
+                ASSERT(usec == SYNCH_NO_TIMEOUT);
+                ASSERT(!(flags & SYNCH_FLAGS_INTERRUPTIBLE));
+                do {
+                        rc = semaphore_trydown(&mtx->sem);
+                } while (SYNCH_FAILED(rc) &&
+                    !(flags & SYNCH_FLAGS_NON_BLOCKING));
+        }
+
+        return rc;
 }
 
-/** Release mutex
+/** Release mutex.
  *
- * Release mutex.
- *
- * @param mtx Mutex.
+ * @param mtx           Mutex.
  */
 void mutex_unlock(mutex_t *mtx)