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

[Madhuparna Bhowmik]

On Tue, Oct 29, 2019 at 2:30 AM Paul E. McKenney <paulmck at kernel.org> wrote:

> 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.
>
Thank you!

>
> > ---
> >  .../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.  ;-)
>
Sure, I will take care of this next time.

>
>                                                         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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