Documentation: RCU: Rename txt files to rst

Rename the following files to reST:
  - rcu.txt
  - listRCU.txt
  - UP.txt

Signed-off-by: Jiunn Chang <c0d1n61at3@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

1 files changed, 0 insertions, 92 deletions

diff --git a/Documentation/RCU/rcu.txt b/Documentation/RCU/rcu.txt
deleted file mode 100644
index 8dfb437dacc3..000000000000
--- a/Documentation/RCU/rcu.txt
+++ /dev/null
@@ -1,92 +0,0 @@
-.. _rcu_doc:
-
-RCU Concepts
-============
-
-The basic idea behind RCU (read-copy update) is to split destructive
-operations into two parts, one that prevents anyone from seeing the data
-item being destroyed, and one that actually carries out the destruction.
-A "grace period" must elapse between the two parts, and this grace period
-must be long enough that any readers accessing the item being deleted have
-since dropped their references.  For example, an RCU-protected deletion
-from a linked list would first remove the item from the list, wait for
-a grace period to elapse, then free the element.  See the
-Documentation/RCU/listRCU.rst file for more information on using RCU with
-linked lists.
-
-Frequently Asked Questions
---------------------------
-
-- Why would anyone want to use RCU?
-
-  The advantage of RCU's two-part approach is that RCU readers need
-  not acquire any locks, perform any atomic instructions, write to
-  shared memory, or (on CPUs other than Alpha) execute any memory
-  barriers.  The fact that these operations are quite expensive
-  on modern CPUs is what gives RCU its performance advantages
-  in read-mostly situations.  The fact that RCU readers need not
-  acquire locks can also greatly simplify deadlock-avoidance code.
-
-- How can the updater tell when a grace period has completed
-  if the RCU readers give no indication when they are done?
-
-  Just as with spinlocks, RCU readers are not permitted to
-  block, switch to user-mode execution, or enter the idle loop.
-  Therefore, as soon as a CPU is seen passing through any of these
-  three states, we know that that CPU has exited any previous RCU
-  read-side critical sections.  So, if we remove an item from a
-  linked list, and then wait until all CPUs have switched context,
-  executed in user mode, or executed in the idle loop, we can
-  safely free up that item.
-
-  Preemptible variants of RCU (CONFIG_PREEMPT_RCU) get the
-  same effect, but require that the readers manipulate CPU-local
-  counters.  These counters allow limited types of blocking within
-  RCU read-side critical sections.  SRCU also uses CPU-local
-  counters, and permits general blocking within RCU read-side
-  critical sections.  These variants of RCU detect grace periods
-  by sampling these counters.
-
-- If I am running on a uniprocessor kernel, which can only do one
-  thing at a time, why should I wait for a grace period?
-
-  See the Documentation/RCU/UP.rst file for more information.
-
-- How can I see where RCU is currently used in the Linux kernel?
-
-  Search for "rcu_read_lock", "rcu_read_unlock", "call_rcu",
-  "rcu_read_lock_bh", "rcu_read_unlock_bh", "srcu_read_lock",
-  "srcu_read_unlock", "synchronize_rcu", "synchronize_net",
-  "synchronize_srcu", and the other RCU primitives.  Or grab one
-  of the cscope databases from:
-
-  (http://www.rdrop.com/users/paulmck/RCU/linuxusage/rculocktab.html).
-
-- What guidelines should I follow when writing code that uses RCU?
-
-  See the checklist.txt file in this directory.
-
-- Why the name "RCU"?
-
-  "RCU" stands for "read-copy update".  The file Documentation/RCU/listRCU.rst
-  has more information on where this name came from, search for
-  "read-copy update" to find it.
-
-- I hear that RCU is patented?  What is with that?
-
-  Yes, it is.  There are several known patents related to RCU,
-  search for the string "Patent" in RTFP.txt to find them.
-  Of these, one was allowed to lapse by the assignee, and the
-  others have been contributed to the Linux kernel under GPL.
-  There are now also LGPL implementations of user-level RCU
-  available (http://liburcu.org/).
-
-- I hear that RCU needs work in order to support realtime kernels?
-
-  Realtime-friendly RCU can be enabled via the CONFIG_PREEMPT_RCU
-  kernel configuration parameter.
-
-- Where can I find more information on RCU?
-
-  See the RTFP.txt file in this directory.
-  Or point your browser at (http://www.rdrop.com/users/paulmck/RCU/).