Changeset 508b0df1 in mainline for uspace/lib/c/include/refcount.h

Timestamp:

2018-09-06T20:21:52Z (6 years ago)

Author:

Jiří Zárevúcky <jiri.zarevucky@…>

Branches:

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

Children:

78de83de, fc10e1b

Parents:

4621d23

git-author:

Jiří Zárevúcky <jiri.zarevucky@…> (2018-08-13 03:53:39)

git-committer:

Jiří Zárevúcky <jiri.zarevucky@…> (2018-09-06 20:21:52)

Message:

Remove uspace <atomic.h>, use <stdatomic.h> instead

File:

• uspace/lib/c/include/refcount.h (modified) (4 diffs)

uspace/lib/c/include/refcount.h

@@ -40 +40 @@
 #define LIBC_REFCOUNT_H_
 
-// TODO: #include <stdatomic.h>
-
 #include <assert.h>
-#include <atomic.h>
+#include <stdatomic.h>
 #include <stdbool.h>
 
 /* Wrapped in a structure to prevent direct manipulation. */
 typedef struct atomic_refcount {
-        //volatile atomic_int __cnt;
-        atomic_t __cnt;
+        volatile atomic_int __cnt;
 } atomic_refcount_t;
 
 static inline void refcount_init(atomic_refcount_t *rc)
 {
-        //atomic_store_explicit(&rc->__cnt, 0, memory_order_relaxed);
-        atomic_set(&rc->__cnt, 0);
+        atomic_store_explicit(&rc->__cnt, 0, memory_order_relaxed);
 }
 
@@ -72 +68 @@
         //      still needs to be synchronized independently of the refcount.
 
-        //int old = atomic_fetch_add_explicit(&rc->__cnt, 1,
-        //    memory_order_relaxed);
-
-        atomic_signed_t old = atomic_postinc(&rc->__cnt);
+        int old = atomic_fetch_add_explicit(&rc->__cnt, 1,
+            memory_order_relaxed);
 
         /* old < 0 indicates that the function is used incorrectly. */
@@ -94 +88 @@
         // XXX: The decrementers don't need to synchronize with each other,
         //      but they do need to synchronize with the one doing deallocation.
-        //int old = atomic_fetch_sub_explicit(&rc->__cnt, 1,
-        //    memory_order_release);
-
-        atomic_signed_t old = atomic_postdec(&rc->__cnt);
+        int old = atomic_fetch_sub_explicit(&rc->__cnt, 1,
+            memory_order_release);
 
         assert(old >= 0);
@@ -104 +96 @@
                 // XXX: We are holding the last reference, so we must now
                 //      synchronize with all the other decrementers.
-                //int val = atomic_load_explicit(&rc->__cnt,
-                //    memory_order_acquire);
-                //assert(val == -1);
-                return true;
+
+                int val = atomic_load_explicit(&rc->__cnt,
+                    memory_order_acquire);
+                assert(val == -1);
+
+                /*
+                 * The compiler probably wouldn't optimize the memory barrier
+                 * away, but better safe than sorry.
+                 */
+                return val < 0;
         }