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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2014-10-19 19:05:22 (GMT)
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2014-11-13 18:34:54 (GMT)
commit1f7870dd8729c64b8472b42440811e7ff94d16a4 (patch)
treeec1ab48f51ecb4846b380bf29b94e65b9e2138d4 /Documentation/atomic_ops.txt
parent8b19d1dead8413442ba0ff0b4e19b08f69d2f1b7 (diff)
documentation: Add atomic_long_t to atomic_ops.txt
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
Diffstat (limited to 'Documentation/atomic_ops.txt')
-rw-r--r--Documentation/atomic_ops.txt12
1 files changed, 8 insertions, 4 deletions
diff --git a/Documentation/atomic_ops.txt b/Documentation/atomic_ops.txt
index 68542fe..183e41b 100644
--- a/Documentation/atomic_ops.txt
+++ b/Documentation/atomic_ops.txt
@@ -7,12 +7,13 @@
maintainers on how to implement atomic counter, bitops, and spinlock
interfaces properly.
- The atomic_t type should be defined as a signed integer.
-Also, it should be made opaque such that any kind of cast to a normal
-C integer type will fail. Something like the following should
-suffice:
+ The atomic_t type should be defined as a signed integer and
+the atomic_long_t type as a signed long integer. Also, they should
+be made opaque such that any kind of cast to a normal C integer type
+will fail. Something like the following should suffice:
typedef struct { int counter; } atomic_t;
+ typedef struct { long counter; } atomic_long_t;
Historically, counter has been declared volatile. This is now discouraged.
See Documentation/volatile-considered-harmful.txt for the complete rationale.
@@ -37,6 +38,9 @@ initializer is used before runtime. If the initializer is used at runtime, a
proper implicit or explicit read memory barrier is needed before reading the
value with atomic_read from another thread.
+As with all of the atomic_ interfaces, replace the leading "atomic_"
+with "atomic_long_" to operate on atomic_long_t.
+
The second interface can be used at runtime, as in:
struct foo { atomic_t counter; };

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