From 34aebfd3bdc93c0c5614f1f61e43b6ddc4be52ae Mon Sep 17 00:00:00 2001
From: Li Zefan <lizf@cn.fujitsu.com>
Date: Thu, 17 Jan 2008 15:21:20 -0800
Subject: [PATCH] Revert "local_t Documentation update"
This reverts commit e1265205c0ee3919c3f2c750662630154c8faab2.
It's a duplicate commit of commit 74beb9db77930be476b267ec8518a642f39a04bf,
resulting in a duplicate section.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
Documentation/local_ops.txt | 23 -----------------------
1 file changed, 23 deletions(-)
diff --git a/Documentation/local_ops.txt b/Documentation/local_ops.txt
index 1a45f11e645e9..4269a1105b378 100644
--- a/Documentation/local_ops.txt
+++ b/Documentation/local_ops.txt
@@ -45,29 +45,6 @@ long fails. The definition looks like :
typedef struct { atomic_long_t a; } local_t;
-* Rules to follow when using local atomic operations
-
-- Variables touched by local ops must be per cpu variables.
-- _Only_ the CPU owner of these variables must write to them.
-- This CPU can use local ops from any context (process, irq, softirq, nmi, ...)
- to update its local_t variables.
-- Preemption (or interrupts) must be disabled when using local ops in
- process context to make sure the process won't be migrated to a
- different CPU between getting the per-cpu variable and doing the
- actual local op.
-- When using local ops in interrupt context, no special care must be
- taken on a mainline kernel, since they will run on the local CPU with
- preemption already disabled. I suggest, however, to explicitly
- disable preemption anyway to make sure it will still work correctly on
- -rt kernels.
-- Reading the local cpu variable will provide the current copy of the
- variable.
-- Reads of these variables can be done from any CPU, because updates to
- "long", aligned, variables are always atomic. Since no memory
- synchronization is done by the writer CPU, an outdated copy of the
- variable can be read when reading some _other_ cpu's variables.
-
-
* Rules to follow when using local atomic operations
- Variables touched by local ops must be per cpu variables.
--
GitLab