linux-kernel - Re: [PATCH v3 01/20] Documentation: locking: Describe seqlock design and usage

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Message-ID: <20200706211659.GA5551@worktop.programming.kicks-ass.net>
Date:   Mon, 6 Jul 2020 23:16:59 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     "Ahmed S. Darwish" <a.darwish@...utronix.de>
Cc:     Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        "Sebastian A. Siewior" <bigeasy@...utronix.de>,
        Steven Rostedt <rostedt@...dmis.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Jonathan Corbet <corbet@....net>, linux-doc@...r.kernel.org
Subject: Re: [PATCH v3 01/20] Documentation: locking: Describe seqlock design
 and usage

On Mon, Jul 06, 2020 at 11:04:39PM +0200, Peter Zijlstra wrote:
> On Tue, Jun 30, 2020 at 07:44:33AM +0200, Ahmed S. Darwish wrote:
> > +Sequence counters (:c:type:`seqcount_t`)
> > +========================================
> 
> > +.. code-block:: c
> 
> I so hate RST, of course it's C. Also, ISTR Jon saying you can leave
> that all out without issue.

Something like the below, and then there's all that :ref: nonsense in
that's unreadable gibberish.


Index: linux-2.6/Documentation/locking/seqlock.rst
===================================================================
--- linux-2.6.orig/Documentation/locking/seqlock.rst
+++ linux-2.6/Documentation/locking/seqlock.rst
@@ -33,10 +33,8 @@ class, it can spin forever and the kerne
 This mechanism cannot be used if the protected data contains pointers,
 as the writer can invalidate a pointer that the reader is following.
 
-.. _seqcount_t:
-
-Sequence counters (:c:type:`seqcount_t`)
-========================================
+Sequence counters (`seqcount_t`)
+================================
 
 This is the the raw counting mechanism, which does not protect against
 multiple writers.  Write side critical sections must thus be serialized
@@ -56,8 +54,6 @@ requirements, use a :ref:`sequential loc
 
 Initialization:
 
-.. code-block:: c
-
 	/* dynamic */
 	seqcount_t foo_seqcount;
 	seqcount_init(&foo_seqcount);
@@ -72,9 +68,6 @@ Initialization:
 
 Write path:
 
-.. _seqcount_write_ops:
-.. code-block:: c
-
 	/* Serialized context with disabled preemption */
 
 	write_seqcount_begin(&foo_seqcount);
@@ -85,9 +78,6 @@ Write path:
 
 Read path:
 
-.. _seqcount_read_ops:
-.. code-block:: c
-
 	do {
 		seq = read_seqcount_begin(&foo_seqcount);
 
@@ -95,9 +85,7 @@ Read path:
 
 	} while (read_seqcount_retry(&foo_seqcount, seq));
 
-.. _seqcount_locktype_t:
-
-Sequence counters with associated locks (:c:type:`seqcount_LOCKTYPE_t`)
+Sequence counters with associated locks (`seqcount_LOCKTYPE_t`)
 -----------------------------------------------------------------------
 
 As :ref:`earlier discussed <seqcount_t>`, seqcount write side critical
@@ -117,11 +105,11 @@ protection is enforced in the write side
 
 The following seqcounts with associated locks are defined:
 
-  - :c:type:`seqcount_spinlock_t`
-  - :c:type:`seqcount_raw_spinlock_t`
-  - :c:type:`seqcount_rwlock_t`
-  - :c:type:`seqcount_mutex_t`
-  - :c:type:`seqcount_ww_mutex_t`
+  - `seqcount_spinlock_t`
+  - `seqcount_raw_spinlock_t`
+  - `seqcount_rwlock_t`
+  - `seqcount_mutex_t`
+  - `seqcount_ww_mutex_t`
 
 The plain seqcount read and write APIs branch out to the specific
 seqcount_LOCKTYPE_t implementation at compile-time. This avoids kernel
@@ -129,8 +117,6 @@ API explosion per each new seqcount LOCK
 
 Initialization (replace "LOCKTYPE" with one of the supported locks):
 
-.. code-block:: c
-
 	/* dynamic */
 	seqcount_LOCKTYPE_t foo_seqcount;
 	seqcount_LOCKTYPE_init(&foo_seqcount, &lock);
@@ -149,9 +135,7 @@ while running from a context with the as
 
 Read path: same as in :ref:`plain seqcount_t <seqcount_read_ops>`.
 
-.. _seqlock_t:
-
-Sequential locks (:c:type:`seqlock_t`)
+Sequential locks (`seqlock_t`)
 ======================================
 
 This contains the :ref:`sequence counting mechanism <seqcount_t>`
@@ -164,8 +148,6 @@ halves respectively.
 
 Initialization:
 
-.. code-block:: c
-
 	/* dynamic */
 	seqlock_t foo_seqlock;
 	seqlock_init(&foo_seqlock);
@@ -180,8 +162,6 @@ Initialization:
 
 Write path:
 
-.. code-block:: c
-
 	write_seqlock(&foo_seqlock);
 
 	/* ... [[write-side critical section]] ... */
@@ -194,8 +174,6 @@ Read path, three categories:
    retry if a writer is in progress by detecting change in the sequence
    number.  Writers do not wait for a sequence reader.
 
-   .. code-block:: c
-
 	do {
 		seq = read_seqbegin(&foo_seqlock);
 
@@ -208,8 +186,6 @@ Read path, three categories:
    from entering its critical section. This read lock is
    exclusive. Unlike rwlock_t, only one locking reader can acquire it.
 
-   .. code-block:: c
-
 	read_seqlock_excl(&foo_seqlock);
 
 	/* ... [[read-side critical section]] ... */
@@ -224,8 +200,6 @@ Read path, three categories:
    the next iteration marker), the lockless read is transformed to a
    full locking read and no retry loop is necessary.
 
-   .. code-block:: c
-
 	/* marker; even initialization */
 	int seq = 0;
 	do {