Changeset 78de83de in mainline

Timestamp:

2018-09-07T15:41:29Z (6 years ago)

Author:

Jiří Zárevúcky <jiri.zarevucky@…>

Branches:

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

Children:

077842c

Parents:

508b0df1

Message:

Improve kernel spinlock and AS refcount.

Location:

kernel/generic

Files:

• include/adt/cht.h (modified) (1 diff)
• include/lib/refcount.h (added)
• include/mm/as.h (modified) (2 diffs)
• include/synch/spinlock.h (modified) (10 diffs)
• src/mm/as.c (modified) (4 diffs)
• src/synch/spinlock.c (modified) (6 diffs)

kernel/generic/include/adt/cht.h

@@ -36 +36 @@
 #define KERN_CONC_HASH_TABLE_H_
 
+#include <atomic.h>
 #include <stdint.h>
 #include <adt/list.h>

kernel/generic/include/mm/as.h

@@ -48 +48 @@
 #include <lib/elf.h>
 #include <arch.h>
+#include <lib/refcount.h>
 
 #define AS                   THE->as
@@ -111 +112 @@
 
         /** Number of references (i.e. tasks that reference this as). */
-        atomic_t refcount;
+        atomic_refcount_t refcount;
 
         mutex_t lock;

kernel/generic/include/synch/spinlock.h

@@ -36 +36 @@
 #define KERN_SPINLOCK_H_
 
+#include <assert.h>
+#include <stdatomic.h>
 #include <stdbool.h>
-#include <barrier.h>
-#include <assert.h>
 #include <preemption.h>
-#include <atomic.h>
 #include <arch/asm.h>
 
@@ -46 +45 @@
 
 typedef struct spinlock {
-        atomic_t val;
+        atomic_flag flag;
 
 #ifdef CONFIG_DEBUG_SPINLOCK
@@ -70 +69 @@
         spinlock_t lock_name = { \
                 .name = desc_name, \
-                .val = { 0 } \
+                .flag = ATOMIC_FLAG_INIT \
         }
 
@@ -76 +75 @@
         static spinlock_t lock_name = { \
                 .name = desc_name, \
-                .val = { 0 } \
+                .flag = ATOMIC_FLAG_INIT \
         }
 
@@ -89 +88 @@
 #define SPINLOCK_INITIALIZE_NAME(lock_name, desc_name) \
         spinlock_t lock_name = { \
-                .val = { 0 } \
+                .flag = ATOMIC_FLAG_INIT \
         }
 
 #define SPINLOCK_STATIC_INITIALIZE_NAME(lock_name, desc_name) \
         static spinlock_t lock_name = { \
-                .val = { 0 } \
+                .flag = ATOMIC_FLAG_INIT \
         }
 
@@ -126 +125 @@
 NO_TRACE static inline void spinlock_unlock_nondebug(spinlock_t *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();
 }
@@ -215 +209 @@
                 .lock = { \
                         .name = desc_name, \
-                        .val = { 0 } \
+                        .flag = ATOMIC_FLAG_INIT \
                 }, \
                 .guard = false, \
@@ -225 +219 @@
                 .lock = { \
                         .name = desc_name, \
-                        .val = { 0 } \
+                        .flag = ATOMIC_FLAG_INIT \
                 }, \
                 .guard = false, \
@@ -236 +230 @@
         irq_spinlock_t lock_name = { \
                 .lock = { \
-                        .val = { 0 } \
+                        .flag = ATOMIC_FLAG_INIT \
                 }, \
                 .guard = false, \
@@ -245 +239 @@
         static irq_spinlock_t lock_name = { \
                 .lock = { \
-                        .val = { 0 } \
+                        .flag = ATOMIC_FLAG_INIT \
                 }, \
                 .guard = false, \

kernel/generic/src/mm/as.c

@@ -163 +163 @@
                 as->asid = ASID_INVALID;
 
-        atomic_set(&as->refcount, 0);
+        refcount_init(&as->refcount);
         as->cpu_refcount = 0;
 
@@ -190 +190 @@
 
         assert(as != AS);
-        assert(atomic_get(&as->refcount) == 0);
+        assert(refcount_unique(&as->refcount));
 
         /*
@@ -267 +267 @@
 NO_TRACE void as_hold(as_t *as)
 {
-        atomic_inc(&as->refcount);
+        refcount_up(&as->refcount);
 }
 
@@ -275 +275 @@
  * destroys the address space.
  *
- * @param asAddress space to be released.
+ * @param as Address space to be released.
  *
  */
 NO_TRACE void as_release(as_t *as)
 {
-        if (atomic_predec(&as->refcount) == 0)
+        if (refcount_down(&as->refcount))
                 as_destroy(as);
 }

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;
 }