[Linux-kernel-mentees] [PATCH] Documentation: RCU: arrayRCU: Converted arrayRCU.txt to arrayRCU.rst

Paul E. McKenney paulmck at kernel.org
Mon Oct 28 21:00:14 UTC 2019


On Tue, Oct 29, 2019 at 01:54:17AM +0530, madhuparnabhowmik04 at gmail.com wrote:
> From: Madhuparna Bhowmik <madhuparnabhowmik04 at gmail.com>
> 
> This patch converts arrayRCU from txt to rst format.
> arrayRCU.rst is also added in the index.rst file.
> 
> Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04 at gmail.com>

Much better, thank you!

I queued this with a small but important change called out below.

> ---
>  .../RCU/{arrayRCU.txt => arrayRCU.rst}         | 18 +++++++++++++-----
>  Documentation/RCU/index.rst                    |  1 +
>  2 files changed, 14 insertions(+), 5 deletions(-)
>  rename Documentation/RCU/{arrayRCU.txt => arrayRCU.rst} (91%)
> 
> diff --git a/Documentation/RCU/arrayRCU.txt b/Documentation/RCU/arrayRCU.rst
> similarity index 91%
> rename from Documentation/RCU/arrayRCU.txt
> rename to Documentation/RCU/arrayRCU.rst
> index f05a9afb2c39..ed5ae24b196e 100644
> --- a/Documentation/RCU/arrayRCU.txt
> +++ b/Documentation/RCU/arrayRCU.rst
> @@ -1,5 +1,7 @@
> -Using RCU to Protect Read-Mostly Arrays
> +.. _array_rcu_doc:
>  
> +Using RCU to Protect Read-Mostly Arrays
> +=======================================
>  
>  Although RCU is more commonly used to protect linked lists, it can
>  also be used to protect arrays.  Three situations are as follows:
> @@ -26,6 +28,7 @@ described in the following sections.
>  
>  
>  Situation 1: Hash Tables
> +------------------------
>  
>  Hash tables are often implemented as an array, where each array entry
>  has a linked-list hash chain.  Each hash chain can be protected by RCU
> @@ -34,6 +37,7 @@ to other array-of-list situations, such as radix trees.
>  
>  
>  Situation 2: Static Arrays
> +--------------------------
>  
>  Static arrays, where the data (rather than a pointer to the data) is
>  located in each array element, and where the array is never resized,
> @@ -41,11 +45,13 @@ have not been used with RCU.  Rik van Riel recommends using seqlock in
>  this situation, which would also have minimal read-side overhead as long
>  as updates are rare.
>  
> -Quick Quiz:  Why is it so important that updates be rare when
> -	     using seqlock?
> +Quick Quiz:  

The above line added trailing whitespace.  I removed it for you, but
please check for this on future submissions.  ;-)

							Thanx, Paul

> +		Why is it so important that updates be rare when using seqlock?
>  
> +:ref:`Answer to Quick Quiz <answer_quick_quiz_seqlock>`
>  
>  Situation 3: Resizeable Arrays
> +------------------------------
>  
>  Use of RCU for resizeable arrays is demonstrated by the grow_ary()
>  function formerly used by the System V IPC code.  The array is used
> @@ -60,7 +66,7 @@ the remainder of the new, updates the ids->entries pointer to point to
>  the new array, and invokes ipc_rcu_putref() to free up the old array.
>  Note that rcu_assign_pointer() is used to update the ids->entries pointer,
>  which includes any memory barriers required on whatever architecture
> -you are running on.
> +you are running on.::
>  
>  	static int grow_ary(struct ipc_ids* ids, int newsize)
>  	{
> @@ -112,7 +118,7 @@ a simple check suffices.  The pointer to the structure corresponding
>  to the desired IPC object is placed in "out", with NULL indicating
>  a non-existent entry.  After acquiring "out->lock", the "out->deleted"
>  flag indicates whether the IPC object is in the process of being
> -deleted, and, if not, the pointer is returned.
> +deleted, and, if not, the pointer is returned.::
>  
>  	struct kern_ipc_perm* ipc_lock(struct ipc_ids* ids, int id)
>  	{
> @@ -144,8 +150,10 @@ deleted, and, if not, the pointer is returned.
>  		return out;
>  	}
>  
> +.. _answer_quick_quiz_seqlock:
>  
>  Answer to Quick Quiz:
> +	Why is it so important that updates be rare when using seqlock?
>  
>  	The reason that it is important that updates be rare when
>  	using seqlock is that frequent updates can livelock readers.
> diff --git a/Documentation/RCU/index.rst b/Documentation/RCU/index.rst
> index 5c99185710fa..8d20d44f8fd4 100644
> --- a/Documentation/RCU/index.rst
> +++ b/Documentation/RCU/index.rst
> @@ -7,6 +7,7 @@ RCU concepts
>  .. toctree::
>     :maxdepth: 3
>  
> +   arrayRCU
>     rcu
>     listRCU
>     UP
> -- 
> 2.17.1
> 


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