Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/djbw/async_tx

[sfrench/cifs-2.6.git] / Documentation / local_ops.txt

diff --git a/Documentation/local_ops.txt b/Documentation/local_ops.txt
index 1a45f11e645e978f445ba7396f0c5411a1695e06..4269a1105b378fafcc689435a2531b9d9d4287db 100644 (file)
--- 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-  synchronization is done by the writer CPU, an outdated copy of the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.