patch-2.4.20 linux-2.4.20/include/asm-alpha/rwsem.h
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- Lines: 44
- Date:
Thu Nov 28 15:53:15 2002
- Orig file:
linux-2.4.19/include/asm-alpha/rwsem.h
- Orig date:
Fri Oct 5 12:10:00 2001
diff -urN linux-2.4.19/include/asm-alpha/rwsem.h linux-2.4.20/include/asm-alpha/rwsem.h
@@ -87,6 +87,24 @@
rwsem_down_read_failed(sem);
}
+/*
+ * trylock for reading -- returns 1 if successful, 0 if contention
+ */
+static inline int __down_read_trylock(struct rw_semaphore *sem)
+{
+ long old, new, res;
+
+ res = sem->count;
+ do {
+ new = res + RWSEM_ACTIVE_READ_BIAS;
+ if (new <= 0)
+ break;
+ old = res;
+ res = cmpxchg(&sem->count, old, new);
+ } while (res != old);
+ return res >= 0 ? 1 : 0;
+}
+
static inline void __down_write(struct rw_semaphore *sem)
{
long oldcount;
@@ -111,6 +129,18 @@
rwsem_down_write_failed(sem);
}
+/*
+ * trylock for writing -- returns 1 if successful, 0 if contention
+ */
+static inline int __down_write_trylock(struct rw_semaphore *sem)
+{
+ long ret = cmpxchg(&sem->count, RWSEM_UNLOCKED_VALUE,
+ RWSEM_ACTIVE_WRITE_BIAS);
+ if (ret == RWSEM_UNLOCKED_VALUE)
+ return 1;
+ return 0;
+}
+
static inline void __up_read(struct rw_semaphore *sem)
{
long oldcount;
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