Changeset 207e8880 in mainline

Timestamp:

2012-12-05T22:36:42Z (11 years ago)

Author:

Adam Hraska <adam.hraska+hos@…>

Branches:

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

Children:

b1c57a8

Parents:

6a585dd

Message:

futex: Switched from using mutexes to spinlocks in futex subsystem.

Location:

kernel/generic

Files:

• include/proc/task.h (modified) (1 diff)
• src/synch/futex.c (modified) (15 diffs)

kernel/generic/include/proc/task.h

@@ -133 +133 @@
                 cht_t ht;
                 /** Serializes access to futex_list.*/
-                mutex_t list_lock;
+                spinlock_t list_lock;
                 /** List of all futexes accesses by this task. */
                 list_t list;

kernel/generic/src/synch/futex.c

@@ -121 +121 @@
  * Acquire task specific TASK->futex_list_lock before this mutex.
  */
-static mutex_t futex_ht_lock;
+SPINLOCK_STATIC_INITIALIZE_NAME(futex_ht_lock, "futex-ht-lock");
 
 /** Global kernel futex hash table. Lock futex_ht_lock before accessing.
@@ -148 +148 @@
 void futex_init(void)
 {
-        mutex_initialize(&futex_ht_lock, MUTEX_PASSIVE);
         hash_table_create(&futex_ht, FUTEX_HT_SIZE, 1, &futex_ht_ops);
 }
@@ -160 +159 @@
         
         list_initialize(&task->futexes->list);
-        mutex_initialize(&task->futexes->list_lock, MUTEX_PASSIVE);
+        spinlock_initialize(&task->futexes->list_lock, "futex-list-lock");
 }
 
@@ -206 +205 @@
         
         /* All threads of this task have terminated. This is the last thread. */
-        mutex_lock(&futexes->list_lock);
+        spinlock_lock(&futexes->list_lock);
         
         list_foreach_safe(futexes->list, cur_link, next_link) {
@@ -222 +221 @@
         }
         
-        mutex_unlock(&futexes->list_lock);
+        spinlock_unlock(&futexes->list_lock);
 }
 
@@ -242 +241 @@
 static void futex_add_ref(futex_t *futex)
 {
-        ASSERT(mutex_locked(&futex_ht_lock));
+        ASSERT(spinlock_locked(&futex_ht_lock));
         ASSERT(0 < futex->refcount);
         ++futex->refcount;
@@ -250 +249 @@
 static void futex_release_ref(futex_t *futex)
 {
-        ASSERT(mutex_locked(&futex_ht_lock));
+        ASSERT(spinlock_locked(&futex_ht_lock));
         ASSERT(0 < futex->refcount);
         
@@ -263 +262 @@
 static void futex_release_ref_locked(futex_t *futex)
 {
-        mutex_lock(&futex_ht_lock);
+        spinlock_lock(&futex_ht_lock);
         futex_release_ref(futex);
-        mutex_unlock(&futex_ht_lock);
+        spinlock_unlock(&futex_ht_lock);
 }
 
@@ -278 +277 @@
         uintptr_t paddr;
 
-        if (!find_futex_paddr(uaddr, &paddr)) 
+        if (!find_futex_paddr(uaddr, &paddr)) {
                 return 0;
+        }
 
         return get_and_cache_futex(paddr, uaddr);
@@ -288 +288 @@
 static bool find_futex_paddr(uintptr_t uaddr, uintptr_t *paddr)
 {
-        page_table_lock(AS, true);
+        spinlock_lock(&futex_ht_lock);
+        page_table_lock(AS, false);
 
         bool found = false;
-        pte_t *t = page_mapping_find(AS, ALIGN_DOWN(uaddr, PAGE_SIZE), false);
+        pte_t *t = page_mapping_find(AS, ALIGN_DOWN(uaddr, PAGE_SIZE), true);
         
         if (t && PTE_VALID(t) && PTE_PRESENT(t)) {
@@ -298 +299 @@
         }
         
-        page_table_unlock(AS, true);
+        page_table_unlock(AS, false);
+        spinlock_unlock(&futex_ht_lock);
         
         return found;
@@ -338 +340 @@
          * if it is not present).
          */
-        mutex_lock(&futex_ht_lock);
+        spinlock_lock(&futex_ht_lock);
         
         link_t *fut_link = hash_table_find(&futex_ht, &phys_addr);
@@ -351 +353 @@
         }
         
-        mutex_unlock(&futex_ht_lock);
+        spinlock_unlock(&futex_ht_lock);
         
         /* 
@@ -366 +368 @@
         /* Cache the mapping from the virtual address to the futex for this task. */
         if (cht_insert_unique(&TASK->futexes->ht, &fut_ptr->cht_link, &dup_link)) {
-                mutex_lock(&TASK->futexes->list_lock);
+                spinlock_lock(&TASK->futexes->list_lock);
                 list_append(&fut_ptr->all_link, &TASK->futexes->list);
-                mutex_unlock(&TASK->futexes->list_lock);
+                spinlock_unlock(&TASK->futexes->list_lock);
         } else {
                 /* Another thread of this task beat us to it. Use that mapping instead.*/
@@ -398 +400 @@
                 return (sysarg_t) ENOENT;
 
-#ifdef CONFIG_UDEBUG
-        udebug_stoppable_begin();
-#endif
         int rc = waitq_sleep_timeout(&futex->wq, 0, SYNCH_FLAGS_INTERRUPTIBLE); 
-#ifdef CONFIG_UDEBUG
-        udebug_stoppable_end();
-#endif
+
         return (sysarg_t) rc;
 }