Changeset fc10e1b in mainline for kernel/generic/src/synch

Timestamp:

2018-09-07T16:34:11Z (7 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.

Location:

kernel/generic/src/synch

Files:

• rcu.c (modified) (5 diffs)
• spinlock.c (modified) (6 diffs)

kernel/generic/src/synch/rcu.c

@@ -312 +312 @@
 
         mutex_initialize(&rcu.barrier_mtx, MUTEX_PASSIVE);
-        atomic_set(&rcu.barrier_wait_cnt, 0);
+        atomic_store(&rcu.barrier_wait_cnt, 0);
         waitq_initialize(&rcu.barrier_wq);
 
@@ -322 +322 @@
         rcu.req_gp_end_cnt = 0;
         rcu.req_expedited_cnt = 0;
-        atomic_set(&rcu.delaying_cpu_cnt, 0);
+        atomic_store(&rcu.delaying_cpu_cnt, 0);
 #endif
 
@@ -594 +594 @@
          * enqueued barrier callbacks start signaling completion.
          */
-        atomic_set(&rcu.barrier_wait_cnt, 1);
+        atomic_store(&rcu.barrier_wait_cnt, 1);
 
         DEFINE_CPU_MASK(cpu_mask);
@@ -1412 +1412 @@
 static void interrupt_delaying_cpus(cpu_mask_t *cpu_mask)
 {
-        atomic_set(&rcu.delaying_cpu_cnt, 0);
+        atomic_store(&rcu.delaying_cpu_cnt, 0);
 
         sample_cpus(cpu_mask, NULL);
@@ -1477 +1477 @@
 static bool wait_for_delaying_cpus(void)
 {
-        int delaying_cpu_cnt = atomic_get(&rcu.delaying_cpu_cnt);
+        int delaying_cpu_cnt = atomic_load(&rcu.delaying_cpu_cnt);
 
         for (int i = 0; i < delaying_cpu_cnt; ++i) {

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;
 }