On Tue, Nov 05, 2019 at 08:49:47PM +0700, Phong Tran wrote:
> On 10/29/19 3:24 AM, madhuparnabhowmik04@xxxxxxxxx wrote:
> > From: Madhuparna Bhowmik <madhuparnabhowmik04@xxxxxxxxx>
> >
> > 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@xxxxxxxxx>
> > ---
> > .../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.
>
> It will be better to have the cross reference for each situation.
>
> Hash Tables
> Static Arrays
> Resizeable Arrays
Madhuparna, could you please put a patch together creating these
cross-references and handling Phong's comments below (probably
by getting rid of the "." so that the resulting ":" doesn't look
strange)?
Then I will fold that patch into your original commit in -rcu and
add Phong's Tested-by.
Thanx, Paul
> > 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:
> > + 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.::
>
> a redundant ":" in here with html page.
>
>
>
>
> > 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.::
>
> same as above
>
>
> Tested-by: Phong Tran <tranmanphong@xxxxxxxxx>
>
> Regards,
> Phong.
>
> > 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
> >
