vserver 1.9.3

[linux-2.6.git] / include / linux / percpu.h

diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index 6aedd71..5451eb1 100644 (file)
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -24,8 +24,8 @@ struct percpu_data {
 
 /* 
  * Use this to get to a cpu's version of the per-cpu object allocated using
- * alloc_percpu.  If you want to get "this cpu's version", maybe you want
- * to use get_cpu_ptr... 
+ * alloc_percpu.  Non-atomic access to the current CPU's version should
+ * probably be combined with get_cpu()/put_cpu().
  */ 
 #define per_cpu_ptr(ptr, cpu)                   \
 ({                                              \
@@ -58,26 +58,4 @@ static inline void free_percpu(const void *ptr)
 #define alloc_percpu(type) \
        ((type *)(__alloc_percpu(sizeof(type), __alignof__(type))))
 
-/* 
- * Use these with alloc_percpu. If
- * 1. You want to operate on memory allocated by alloc_percpu (dereference
- *    and read/modify/write)  AND 
- * 2. You want "this cpu's version" of the object AND 
- * 3. You want to do this safely since:
- *    a. On multiprocessors, you don't want to switch between cpus after 
- *    you've read the current processor id due to preemption -- this would 
- *    take away the implicit  advantage to not have any kind of traditional 
- *    serialization for per-cpu data
- *    b. On uniprocessors, you don't want another kernel thread messing
- *    up with the same per-cpu data due to preemption
- *    
- * So, Use get_cpu_ptr to disable preemption and get pointer to the 
- * local cpu version of the per-cpu object. Use put_cpu_ptr to enable
- * preemption.  Operations on per-cpu data between get_ and put_ is
- * then considered to be safe. And ofcourse, "Thou shalt not sleep between 
- * get_cpu_ptr and put_cpu_ptr"
- */
-#define get_cpu_ptr(ptr) per_cpu_ptr(ptr, get_cpu())
-#define put_cpu_ptr(ptr) put_cpu()
-
 #endif /* __LINUX_PERCPU_H */