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documentation: Make sample code and documentation consistent 

In the chapter 'analogy with reader-writer locking', the sample
code uses spinlock_t in reader-writer case. Just correct it so
that we can read the document easily.

Signed-off-by: Yao Dongdong <yaodongdong@huawei.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Yao Dongdong 2016-03-07 16:02:14 +08:00 committed by Paul E. McKenney
parent 274529ba9b
commit 70946a44de
1 changed files with 15 additions and 7 deletions
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22
Documentation/RCU/whatisRCU.txt
View File

@ -681,22 +681,30 @@ Although RCU can be used in many different ways, a very common use of
RCU is analogous to reader-writer locking. The following unified
diff shows how closely related RCU and reader-writer locking can be.
@@ -5,5 +5,5 @@ struct el {
int data;
/* Other data fields */
};
-rwlock_t listmutex;
+spinlock_t listmutex;
struct el head;
@@ -13,15 +14,15 @@
struct list_head *lp;
struct el *p;
- read_lock();
- read_lock(&listmutex);
- list_for_each_entry(p, head, lp) {
+ rcu_read_lock();
+ list_for_each_entry_rcu(p, head, lp) {
if (p->key == key) {
*result = p->data;
- read_unlock();
- read_unlock(&listmutex);
+ rcu_read_unlock();
return 1;
}
}
- read_unlock();
- read_unlock(&listmutex);
+ rcu_read_unlock();
return 0;
}
@ -732,7 +740,7 @@ Or, for those who prefer a side-by-side listing:
5 int data; 5 int data;
6 /* Other data fields */ 6 /* Other data fields */
7 }; 7 };
8 spinlock_t listmutex; 8 spinlock_t listmutex;
8 rwlock_t listmutex; 8 spinlock_t listmutex;
9 struct el head; 9 struct el head;
1 int search(long key, int *result) 1 int search(long key, int *result)
@ -740,15 +748,15 @@ Or, for those who prefer a side-by-side listing:
3 struct list_head *lp; 3 struct list_head *lp;
4 struct el *p; 4 struct el *p;
5 5
6 read_lock(); 6 rcu_read_lock();
6 read_lock(&listmutex); 6 rcu_read_lock();
7 list_for_each_entry(p, head, lp) { 7 list_for_each_entry_rcu(p, head, lp) {
8 if (p->key == key) { 8 if (p->key == key) {
9 *result = p->data; 9 *result = p->data;
10 read_unlock(); 10 rcu_read_unlock();
10 read_unlock(&listmutex); 10 rcu_read_unlock();
11 return 1; 11 return 1;
12 } 12 }
13 } 13 }
14 read_unlock(); 14 rcu_read_unlock();
14 read_unlock(&listmutex); 14 rcu_read_unlock();
15 return 0; 15 return 0;
16 } 16 }