MCS locks properly disable thread migration
[akaros.git] / user / parlib / mcs.c
index f74262c..a8fbbe7 100644 (file)
@@ -3,6 +3,7 @@
 #include <arch/atomic.h>
 #include <string.h>
 #include <stdlib.h>
+#include <uthread.h>
 
 // MCS locks
 void mcs_lock_init(struct mcs_lock *lock)
@@ -13,7 +14,7 @@ void mcs_lock_init(struct mcs_lock *lock)
 static inline mcs_lock_qnode_t *mcs_qnode_swap(mcs_lock_qnode_t **addr,
                                                mcs_lock_qnode_t *val)
 {
-       return (mcs_lock_qnode_t*)atomic_swap((int*)addr,(int)val);
+       return (mcs_lock_qnode_t*)atomic_swap_ptr((void**)addr, val);
 }
 
 void mcs_lock_lock(struct mcs_lock *lock, struct mcs_lock_qnode *qnode)
@@ -54,16 +55,30 @@ void mcs_lock_unlock(struct mcs_lock *lock, struct mcs_lock_qnode *qnode)
  * (when switching into the TLS, etc). */
 void mcs_lock_notifsafe(struct mcs_lock *lock, struct mcs_lock_qnode *qnode)
 {
-       if (!in_vcore_context())
+       if (!in_vcore_context()) {
+               if (current_uthread)
+                       current_uthread->flags |= UTHREAD_DONT_MIGRATE;
+               wmb();
                disable_notifs(vcore_id());
+               wmb();
+               if (current_uthread)
+                       current_uthread->flags &= ~UTHREAD_DONT_MIGRATE;
+       }
        mcs_lock_lock(lock, qnode);
 }
 
 void mcs_unlock_notifsafe(struct mcs_lock *lock, struct mcs_lock_qnode *qnode)
 {
        mcs_lock_unlock(lock, qnode);
-       if (!in_vcore_context())
+       if (!in_vcore_context() && in_multi_mode()) {
+               if (current_uthread)
+                       current_uthread->flags |= UTHREAD_DONT_MIGRATE;
+               wmb();
                enable_notifs(vcore_id());
+               wmb();
+               if (current_uthread)
+                       current_uthread->flags &= ~UTHREAD_DONT_MIGRATE;
+       }
 }
 
 // MCS dissemination barrier!