1 files changed, 49 insertions, 6 deletions

diff --git a/kern/mutex/mutex_plain.c b/kern/mutex/mutex_plain.c
index 5e4ba537..58fc4878 100644
--- a/kern/mutex/mutex_plain.c
+++ b/kern/mutex/mutex_plain.c
@@ -15,20 +15,25 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <assert.h>
 #include <stdbool.h>
 #include <stddef.h>
+#include <stdint.h>
 
 #include <kern/atomic.h>
 #include <kern/mutex.h>
 #include <kern/mutex_types.h>
 #include <kern/sleepq.h>
 
-void
-mutex_plain_lock_slow(struct mutex *mutex)
+static int
+mutex_plain_lock_slow_common(struct mutex *mutex, bool timed, uint64_t ticks)
 {
     unsigned int state;
     struct sleepq *sleepq;
     unsigned long flags;
+    int error;
+
+    error = 0;
 
     sleepq = sleepq_lend(mutex, false, &flags);
 
@@ -39,14 +44,49 @@ mutex_plain_lock_slow(struct mutex *mutex)
             break;
         }
 
-        sleepq_wait(sleepq, "mutex");
+        if (!timed) {
+            sleepq_wait(sleepq, "mutex");
+        } else {
+            error = sleepq_timedwait(sleepq, "mutex", ticks);
+
+            if (error) {
+                break;
+            }
+        }
+    }
+
+    if (error) {
+        if (sleepq_empty(sleepq)) {
+            atomic_cas(&mutex->state, MUTEX_CONTENDED,
+                       MUTEX_LOCKED, ATOMIC_RELAXED);
+        }
+
+        goto out;
     }
 
     if (sleepq_empty(sleepq)) {
         atomic_store(&mutex->state, MUTEX_LOCKED, ATOMIC_RELAXED);
     }
 
+out:
     sleepq_return(sleepq, flags);
+
+    return error;
+}
+
+void
+mutex_plain_lock_slow(struct mutex *mutex)
+{
+    int error;
+
+    error = mutex_plain_lock_slow_common(mutex, false, 0);
+    assert(!error);
+}
+
+int
+mutex_plain_timedlock_slow(struct mutex *mutex, uint64_t ticks)
+{
+    return mutex_plain_lock_slow_common(mutex, true, ticks);
 }
 
 void
@@ -57,8 +97,11 @@ mutex_plain_unlock_slow(struct mutex *mutex)
 
     sleepq = sleepq_acquire(mutex, false, &flags);
 
-    if (sleepq != NULL) {
-        sleepq_signal(sleepq);
-        sleepq_release(sleepq, flags);
+    if (sleepq == NULL) {
+        return;
     }
+
+    sleepq_signal(sleepq);
+
+    sleepq_release(sleepq, flags);
 }