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Message-Id: <1460474301-22998-1-git-send-email-paulmck@linux.vnet.ibm.com>
Date: Tue, 12 Apr 2016 08:18:12 -0700
From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To: linux-kernel@...r.kernel.org
Cc: mingo@...nel.org, jiangshanlai@...il.com, dipankar@...ibm.com,
akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
dvhart@...ux.intel.com, fweisbec@...il.com, oleg@...hat.com,
bobby.prani@...il.com, Yao Dongdong <yaodongdong@...wei.com>,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 01/10] documentation: Make sample code and documentation consistent
From: Yao Dongdong <yaodongdong@...wei.com>
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@...wei.com>
Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
Documentation/RCU/whatisRCU.txt | 22 +++++++++++++++-------
1 file changed, 15 insertions(+), 7 deletions(-)
diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisRCU.txt
index dc49c6712b17..111770ffa10e 100644
--- a/Documentation/RCU/whatisRCU.txt
+++ b/Documentation/RCU/whatisRCU.txt
@@ -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 }
--
2.5.2
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