Changeset fc10e1b in mainline for kernel/generic/src/synch/spinlock.c

Timestamp:

2018-09-07T16:34:11Z (6 years ago)

Author:

Jiří Zárevúcky <jiri.zarevucky@…>

Branches:

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

Children:

d2c91ab

Parents:

508b0df1 (diff), e90cfa6 (diff)
Note: this is a merge changeset, the changes displayed below correspond to the merge itself.
Use the (diff) links above to see all the changes relative to each parent.

Message:

Merge branch 'atomic'

Use more of <stdatomic.h> in kernel. Increment/decrement macros kept because
the are handy. atomic_t currently kept because I'm way too lazy to go through
all uses and think about the most appropriate replacement.

File:

• kernel/generic/src/synch/spinlock.c (modified) (6 diffs)

kernel/generic/src/synch/spinlock.c

@@ -56 +56 @@
 void spinlock_initialize(spinlock_t *lock, const char *name)
 {
-        atomic_set(&lock->val, 0);
+        atomic_flag_clear_explicit(&lock->flag, memory_order_relaxed);
 #ifdef CONFIG_DEBUG_SPINLOCK
         lock->name = name;
@@ -79 +79 @@
 
         preemption_disable();
-        while (test_and_set(&lock->val)) {
+        while (atomic_flag_test_and_set_explicit(&lock->flag, memory_order_acquire)) {
                 /*
                  * We need to be careful about particular locks
@@ -115 +115 @@
         if (deadlock_reported)
                 printf("cpu%u: not deadlocked\n", CPU->id);
-
-        /*
-         * Prevent critical section code from bleeding out this way up.
-         */
-        CS_ENTER_BARRIER();
 }
 
@@ -132 +127 @@
         ASSERT_SPINLOCK(spinlock_locked(lock), lock);
 
-        /*
-         * Prevent critical section code from bleeding out this way down.
-         */
-        CS_LEAVE_BARRIER();
-
-        atomic_set(&lock->val, 0);
+        atomic_flag_clear_explicit(&lock->flag, memory_order_release);
         preemption_enable();
 }
@@ -156 +146 @@
 {
         preemption_disable();
-        bool ret = !test_and_set(&lock->val);
-
-        /*
-         * Prevent critical section code from bleeding out this way up.
-         */
-        CS_ENTER_BARRIER();
+        bool ret = !atomic_flag_test_and_set_explicit(&lock->flag, memory_order_acquire);
 
         if (!ret)
@@ -176 +161 @@
 bool spinlock_locked(spinlock_t *lock)
 {
-        return atomic_get(&lock->val) != 0;
+        // XXX: Atomic flag doesn't support simple atomic read (by design),
+        //      so instead we test_and_set and then clear if necessary.
+        //      This function is only used inside assert, so we don't need
+        //      any preemption_disable/enable here.
+
+        bool ret = atomic_flag_test_and_set_explicit(&lock->flag, memory_order_relaxed);
+        if (!ret)
+                atomic_flag_clear_explicit(&lock->flag, memory_order_relaxed);
+        return ret;
 }