Date:   Mon, 10 May 2021 17:05:25 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Cc:     Linux Doc Mailing List <linux-doc@...r.kernel.org>,
        Jonathan Corbet <corbet@....net>,
        Nícolas F. R. A. Prado 
        <nfraprado@...tonmail.com>,
        Joel Fernandes <joel@...lfernandes.org>,
        Josh Triplett <josh@...htriplett.org>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Steven Rostedt <rostedt@...dmis.org>,
        Takashi Iwai <tiwai@...e.de>, linux-kernel@...r.kernel.org,
        rcu@...r.kernel.org
Subject: Re: [PATCH 53/53] docs: RCU: avoid using UTF-8 chars

On Mon, May 10, 2021 at 12:27:05PM +0200, Mauro Carvalho Chehab wrote:
> While UTF-8 characters can be used at the Linux documentation,
> the best is to use them only when ASCII doesn't offer a good replacement.
> So, replace the occurences of the following UTF-8 characters:
> 
> 	- U+00a0 (' '): NO-BREAK SPACE
> 	- U+2013 ('–'): EN DASH
> 	- U+2014 ('—'): EM DASH
> 	- U+201c ('“'): LEFT DOUBLE QUOTATION MARK
> 	- U+201d ('”'): RIGHT DOUBLE QUOTATION MARK
> 
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>

Acked-by: Paul E. McKenney <paulmck@...nel.org>

> ---
>  .../Data-Structures/Data-Structures.rst       |  52 ++++----
>  .../Expedited-Grace-Periods.rst               |  40 +++---
>  .../Tree-RCU-Memory-Ordering.rst              |  10 +-
>  .../RCU/Design/Requirements/Requirements.rst  | 126 +++++++++---------
>  4 files changed, 114 insertions(+), 114 deletions(-)
> 
> diff --git a/Documentation/RCU/Design/Data-Structures/Data-Structures.rst b/Documentation/RCU/Design/Data-Structures/Data-Structures.rst
> index f4efd6897b09..e95c6c8eeb6a 100644
> --- a/Documentation/RCU/Design/Data-Structures/Data-Structures.rst
> +++ b/Documentation/RCU/Design/Data-Structures/Data-Structures.rst
> @@ -301,7 +301,7 @@ The ``->gp_max`` field tracks the duration of the longest grace period
>  in jiffies. It is protected by the root ``rcu_node``'s ``->lock``.
>  
>  The ``->name`` and ``->abbr`` fields distinguish between preemptible RCU
> -(“rcu_preempt” and “p”) and non-preemptible RCU (“rcu_sched” and “s”).
> +("rcu_preempt" and "p") and non-preemptible RCU ("rcu_sched" and "s").
>  These fields are used for diagnostic and tracing purposes.
>  
>  The ``rcu_node`` Structure
> @@ -456,21 +456,21 @@ expedited grace periods, respectively.
>  | Lockless grace-period computation! Such a tantalizing possibility!    |
>  | But consider the following sequence of events:                        |
>  |                                                                       |
> -| #. CPU 0 has been in dyntick-idle mode for quite some time. When it   |
> +| #. CPU 0 has been in dyntick-idle mode for quite some time. When it   |
>  |    wakes up, it notices that the current RCU grace period needs it to |
>  |    report in, so it sets a flag where the scheduling clock interrupt  |
>  |    will find it.                                                      |
> -| #. Meanwhile, CPU 1 is running ``force_quiescent_state()``, and       |
> -|    notices that CPU 0 has been in dyntick idle mode, which qualifies  |
> +| #. Meanwhile, CPU 1 is running ``force_quiescent_state()``, and       |
> +|    notices that CPU 0 has been in dyntick idle mode, which qualifies  |
>  |    as an extended quiescent state.                                    |
> -| #. CPU 0's scheduling clock interrupt fires in the middle of an RCU   |
> +| #. CPU 0's scheduling clock interrupt fires in the middle of an RCU   |
>  |    read-side critical section, and notices that the RCU core needs    |
>  |    something, so commences RCU softirq processing.                    |
> -| #. CPU 0's softirq handler executes and is just about ready to report |
> +| #. CPU 0's softirq handler executes and is just about ready to report |
>  |    its quiescent state up the ``rcu_node`` tree.                      |
> -| #. But CPU 1 beats it to the punch, completing the current grace      |
> +| #. But CPU 1 beats it to the punch, completing the current grace      |
>  |    period and starting a new one.                                     |
> -| #. CPU 0 now reports its quiescent state for the wrong grace period.  |
> +| #. CPU 0 now reports its quiescent state for the wrong grace period.  |
>  |    That grace period might now end before the RCU read-side critical  |
>  |    section. If that happens, disaster will ensue.                     |
>  |                                                                       |
> @@ -515,18 +515,18 @@ removes itself from the ``->blkd_tasks`` list, then that task must
>  advance the pointer to the next task on the list, or set the pointer to
>  ``NULL`` if there are no subsequent tasks on the list.
>  
> -For example, suppose that tasks T1, T2, and T3 are all hard-affinitied
> -to the largest-numbered CPU in the system. Then if task T1 blocked in an
> +For example, suppose that tasks T1, T2, and T3 are all hard-affinitied
> +to the largest-numbered CPU in the system. Then if task T1 blocked in an
>  RCU read-side critical section, then an expedited grace period started,
> -then task T2 blocked in an RCU read-side critical section, then a normal
> -grace period started, and finally task 3 blocked in an RCU read-side
> +then task T2 blocked in an RCU read-side critical section, then a normal
> +grace period started, and finally task 3 blocked in an RCU read-side
>  critical section, then the state of the last leaf ``rcu_node``
>  structure's blocked-task list would be as shown below:
>  
>  .. kernel-figure:: blkd_task.svg
>  
> -Task T1 is blocking both grace periods, task T2 is blocking only the
> -normal grace period, and task T3 is blocking neither grace period. Note
> +Task T1 is blocking both grace periods, task T2 is blocking only the
> +normal grace period, and task T3 is blocking neither grace period. Note
>  that these tasks will not remove themselves from this list immediately
>  upon resuming execution. They will instead remain on the list until they
>  execute the outermost ``rcu_read_unlock()`` that ends their RCU
> @@ -611,8 +611,8 @@ expressions as follows:
>     66 #endif
>  
>  The maximum number of levels in the ``rcu_node`` structure is currently
> -limited to four, as specified by lines 21-24 and the structure of the
> -subsequent “if” statement. For 32-bit systems, this allows
> +limited to four, as specified by lines 21-24 and the structure of the
> +subsequent "if" statement. For 32-bit systems, this allows
>  16*32*32*32=524,288 CPUs, which should be sufficient for the next few
>  years at least. For 64-bit systems, 16*64*64*64=4,194,304 CPUs is
>  allowed, which should see us through the next decade or so. This
> @@ -638,9 +638,9 @@ fields. The number of CPUs per leaf ``rcu_node`` structure is therefore
>  limited to 16 given the default value of ``CONFIG_RCU_FANOUT_LEAF``. If
>  ``CONFIG_RCU_FANOUT_LEAF`` is unspecified, the value selected is based
>  on the word size of the system, just as for ``CONFIG_RCU_FANOUT``.
> -Lines 11-19 perform this computation.
> +Lines 11-19 perform this computation.
>  
> -Lines 21-24 compute the maximum number of CPUs supported by a
> +Lines 21-24 compute the maximum number of CPUs supported by a
>  single-level (which contains a single ``rcu_node`` structure),
>  two-level, three-level, and four-level ``rcu_node`` tree, respectively,
>  given the fanout specified by ``RCU_FANOUT`` and ``RCU_FANOUT_LEAF``.
> @@ -649,18 +649,18 @@ These numbers of CPUs are retained in the ``RCU_FANOUT_1``,
>  variables, respectively.
>  
>  These variables are used to control the C-preprocessor ``#if`` statement
> -spanning lines 26-66 that computes the number of ``rcu_node`` structures
> +spanning lines 26-66 that computes the number of ``rcu_node`` structures
>  required for each level of the tree, as well as the number of levels
>  required. The number of levels is placed in the ``NUM_RCU_LVLS``
> -C-preprocessor variable by lines 27, 35, 44, and 54. The number of
> +C-preprocessor variable by lines 27, 35, 44, and 54. The number of
>  ``rcu_node`` structures for the topmost level of the tree is always
>  exactly one, and this value is unconditionally placed into
> -``NUM_RCU_LVL_0`` by lines 28, 36, 45, and 55. The rest of the levels
> +``NUM_RCU_LVL_0`` by lines 28, 36, 45, and 55. The rest of the levels
>  (if any) of the ``rcu_node`` tree are computed by dividing the maximum
>  number of CPUs by the fanout supported by the number of levels from the
>  current level down, rounding up. This computation is performed by
> -lines 37, 46-47, and 56-58. Lines 31-33, 40-42, 50-52, and 62-63 create
> -initializers for lockdep lock-class names. Finally, lines 64-66 produce
> +lines 37, 46-47, and 56-58. Lines 31-33, 40-42, 50-52, and 62-63 create
> +initializers for lockdep lock-class names. Finally, lines 64-66 produce
>  an error if the maximum number of CPUs is too large for the specified
>  fanout.
>  
> @@ -716,13 +716,13 @@ In this figure, the ``->head`` pointer references the first RCU callback
>  in the list. The ``->tails[RCU_DONE_TAIL]`` array element references the
>  ``->head`` pointer itself, indicating that none of the callbacks is
>  ready to invoke. The ``->tails[RCU_WAIT_TAIL]`` array element references
> -callback CB 2's ``->next`` pointer, which indicates that CB 1 and CB 2
> +callback CB 2's ``->next`` pointer, which indicates that CB 1 and CB 2
>  are both waiting on the current grace period, give or take possible
>  disagreements about exactly which grace period is the current one. The
>  ``->tails[RCU_NEXT_READY_TAIL]`` array element references the same RCU
>  callback that ``->tails[RCU_WAIT_TAIL]`` does, which indicates that
>  there are no callbacks waiting on the next RCU grace period. The
> -``->tails[RCU_NEXT_TAIL]`` array element references CB 4's ``->next``
> +``->tails[RCU_NEXT_TAIL]`` array element references CB 4's ``->next``
>  pointer, indicating that all the remaining RCU callbacks have not yet
>  been assigned to an RCU grace period. Note that the
>  ``->tails[RCU_NEXT_TAIL]`` array element always references the last RCU
> @@ -1031,7 +1031,7 @@ field to record the offset of the ``rcu_head`` structure within the
>  enclosing RCU-protected data structure.
>  
>  Both of these fields are used internally by RCU. From the viewpoint of
> -RCU users, this structure is an opaque “cookie”.
> +RCU users, this structure is an opaque "cookie".
>  
>  +-----------------------------------------------------------------------+
>  | **Quick Quiz**:                                                       |
> diff --git a/Documentation/RCU/Design/Expedited-Grace-Periods/Expedited-Grace-Periods.rst b/Documentation/RCU/Design/Expedited-Grace-Periods/Expedited-Grace-Periods.rst
> index 6f89cf1e567d..742921a7532b 100644
> --- a/Documentation/RCU/Design/Expedited-Grace-Periods/Expedited-Grace-Periods.rst
> +++ b/Documentation/RCU/Design/Expedited-Grace-Periods/Expedited-Grace-Periods.rst
> @@ -304,8 +304,8 @@ representing the elements of the ``->exp_wq[]`` array.
>  
>  .. kernel-figure:: Funnel0.svg
>  
> -The next diagram shows the situation after the arrival of Task A and
> -Task B at the leftmost and rightmost leaf ``rcu_node`` structures,
> +The next diagram shows the situation after the arrival of Task A and
> +Task B at the leftmost and rightmost leaf ``rcu_node`` structures,
>  respectively. The current value of the ``rcu_state`` structure's
>  ``->expedited_sequence`` field is zero, so adding three and clearing the
>  bottom bit results in the value two, which both tasks record in the
> @@ -313,13 +313,13 @@ bottom bit results in the value two, which both tasks record in the
>  
>  .. kernel-figure:: Funnel1.svg
>  
> -Each of Tasks A and B will move up to the root ``rcu_node`` structure.
> -Suppose that Task A wins, recording its desired grace-period sequence
> +Each of Tasks A and B will move up to the root ``rcu_node`` structure.
> +Suppose that Task A wins, recording its desired grace-period sequence
>  number and resulting in the state shown below:
>  
>  .. kernel-figure:: Funnel2.svg
>  
> -Task A now advances to initiate a new grace period, while Task B moves
> +Task A now advances to initiate a new grace period, while Task B moves
>  up to the root ``rcu_node`` structure, and, seeing that its desired
>  sequence number is already recorded, blocks on ``->exp_wq[1]``.
>  
> @@ -340,7 +340,7 @@ sequence number is already recorded, blocks on ``->exp_wq[1]``.
>  | ``->exp_wq[1]``.                                                      |
>  +-----------------------------------------------------------------------+
>  
> -If Tasks C and D also arrive at this point, they will compute the same
> +If Tasks C and D also arrive at this point, they will compute the same
>  desired grace-period sequence number, and see that both leaf
>  ``rcu_node`` structures already have that value recorded. They will
>  therefore block on their respective ``rcu_node`` structures'
> @@ -348,52 +348,52 @@ therefore block on their respective ``rcu_node`` structures'
>  
>  .. kernel-figure:: Funnel3.svg
>  
> -Task A now acquires the ``rcu_state`` structure's ``->exp_mutex`` and
> +Task A now acquires the ``rcu_state`` structure's ``->exp_mutex`` and
>  initiates the grace period, which increments ``->expedited_sequence``.
> -Therefore, if Tasks E and F arrive, they will compute a desired sequence
> +Therefore, if Tasks E and F arrive, they will compute a desired sequence
>  number of 4 and will record this value as shown below:
>  
>  .. kernel-figure:: Funnel4.svg
>  
> -Tasks E and F will propagate up the ``rcu_node`` combining tree, with
> -Task F blocking on the root ``rcu_node`` structure and Task E wait for
> -Task A to finish so that it can start the next grace period. The
> +Tasks E and F will propagate up the ``rcu_node`` combining tree, with
> +Task F blocking on the root ``rcu_node`` structure and Task E wait for
> +Task A to finish so that it can start the next grace period. The
>  resulting state is as shown below:
>  
>  .. kernel-figure:: Funnel5.svg
>  
> -Once the grace period completes, Task A starts waking up the tasks
> +Once the grace period completes, Task A starts waking up the tasks
>  waiting for this grace period to complete, increments the
>  ``->expedited_sequence``, acquires the ``->exp_wake_mutex`` and then
>  releases the ``->exp_mutex``. This results in the following state:
>  
>  .. kernel-figure:: Funnel6.svg
>  
> -Task E can then acquire ``->exp_mutex`` and increment
> -``->expedited_sequence`` to the value three. If new tasks G and H arrive
> +Task E can then acquire ``->exp_mutex`` and increment
> +``->expedited_sequence`` to the value three. If new tasks G and H arrive
>  and moves up the combining tree at the same time, the state will be as
>  follows:
>  
>  .. kernel-figure:: Funnel7.svg
>  
>  Note that three of the root ``rcu_node`` structure's waitqueues are now
> -occupied. However, at some point, Task A will wake up the tasks blocked
> +occupied. However, at some point, Task A will wake up the tasks blocked
>  on the ``->exp_wq`` waitqueues, resulting in the following state:
>  
>  .. kernel-figure:: Funnel8.svg
>  
> -Execution will continue with Tasks E and H completing their grace
> +Execution will continue with Tasks E and H completing their grace
>  periods and carrying out their wakeups.
>  
>  +-----------------------------------------------------------------------+
>  | **Quick Quiz**:                                                       |
>  +-----------------------------------------------------------------------+
> -| What happens if Task A takes so long to do its wakeups that Task E's  |
> +| What happens if Task A takes so long to do its wakeups that Task E's  |
>  | grace period completes?                                               |
>  +-----------------------------------------------------------------------+
>  | **Answer**:                                                           |
>  +-----------------------------------------------------------------------+
> -| Then Task E will block on the ``->exp_wake_mutex``, which will also   |
> +| Then Task E will block on the ``->exp_wake_mutex``, which will also   |
>  | prevent it from releasing ``->exp_mutex``, which in turn will prevent |
>  | the next grace period from starting. This last is important in        |
>  | preventing overflow of the ``->exp_wq[]`` array.                      |
> @@ -464,8 +464,8 @@ code need not worry about POSIX signals. Unfortunately, it has the
>  corresponding disadvantage that workqueues cannot be used until they are
>  initialized, which does not happen until some time after the scheduler
>  spawns the first task. Given that there are parts of the kernel that
> -really do want to execute grace periods during this mid-boot “dead
> -zone”, expedited grace periods must do something else during thie time.
> +really do want to execute grace periods during this mid-boot "dead
> +zone", expedited grace periods must do something else during thie time.
>  
>  What they do is to fall back to the old practice of requiring that the
>  requesting task drive the expedited grace period, as was the case before
> diff --git a/Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.rst b/Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.rst
> index a648b423ba0e..d76c6bfdc659 100644
> --- a/Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.rst
> +++ b/Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.rst
> @@ -215,7 +215,7 @@ newly arrived RCU callbacks against future grace periods:
>     43 }
>  
>  But the only part of ``rcu_prepare_for_idle()`` that really matters for
> -this discussion are lines 37–39. We will therefore abbreviate this
> +this discussion are lines 37-39. We will therefore abbreviate this
>  function as follows:
>  
>  .. kernel-figure:: rcu_node-lock.svg
> @@ -418,7 +418,7 @@ wait on.
>  | It is indeed not necessary for the grace period to wait on such a     |
>  | critical section. However, it is permissible to wait on it. And it is |
>  | furthermore important to wait on it, as this lazy approach is far     |
> -| more scalable than a “big bang” all-at-once grace-period start could  |
> +| more scalable than a "big bang" all-at-once grace-period start could  |
>  | possibly be.                                                          |
>  +-----------------------------------------------------------------------+
>  
> @@ -448,7 +448,7 @@ proceeds upwards from that point, and the ``rcu_node`` ``->lock``
>  guarantees that the first CPU's quiescent state happens before the
>  remainder of the second CPU's traversal. Applying this line of thought
>  repeatedly shows that all CPUs' quiescent states happen before the last
> -CPU traverses through the root ``rcu_node`` structure, the “last CPU”
> +CPU traverses through the root ``rcu_node`` structure, the "last CPU"
>  being the one that clears the last bit in the root ``rcu_node``
>  structure's ``->qsmask`` field.
>  
> @@ -501,8 +501,8 @@ Forcing Quiescent States
>  
>  As noted above, idle and offline CPUs cannot report their own quiescent
>  states, and therefore the grace-period kernel thread must do the
> -reporting on their behalf. This process is called “forcing quiescent
> -states”, it is repeated every few jiffies, and its ordering effects are
> +reporting on their behalf. This process is called "forcing quiescent
> +states", it is repeated every few jiffies, and its ordering effects are
>  shown below:
>  
>  .. kernel-figure:: TreeRCU-gp-fqs.svg
> diff --git a/Documentation/RCU/Design/Requirements/Requirements.rst b/Documentation/RCU/Design/Requirements/Requirements.rst
> index 38a39476fc24..a3493b34f3dd 100644
> --- a/Documentation/RCU/Design/Requirements/Requirements.rst
> +++ b/Documentation/RCU/Design/Requirements/Requirements.rst
> @@ -4,7 +4,7 @@ A Tour Through RCU's Requirements
>  
>  Copyright IBM Corporation, 2015
>  
> -Author: Paul E. McKenney
> +Author: Paul E. McKenney
>  
>  The initial version of this document appeared in the
>  `LWN <https://lwn.net/>`_ on those articles:
> @@ -66,7 +66,7 @@ Grace-Period Guarantee
>  
>  RCU's grace-period guarantee is unusual in being premeditated: Jack
>  Slingwine and I had this guarantee firmly in mind when we started work
> -on RCU (then called “rclock”) in the early 1990s. That said, the past
> +on RCU (then called "rclock") in the early 1990s. That said, the past
>  two decades of experience with RCU have produced a much more detailed
>  understanding of this guarantee.
>  
> @@ -102,7 +102,7 @@ overhead to readers, for example:
>        15   WRITE_ONCE(y, 1);
>        16 }
>  
> -Because the synchronize_rcu() on line 14 waits for all pre-existing
> +Because the synchronize_rcu() on line 14 waits for all pre-existing
>  readers, any instance of thread0() that loads a value of zero from
>  ``x`` must complete before thread1() stores to ``y``, so that
>  instance must also load a value of zero from ``y``. Similarly, any
> @@ -178,7 +178,7 @@ little or no synchronization overhead in do_something_dlm().
>  +-----------------------------------------------------------------------+
>  | **Quick Quiz**:                                                       |
>  +-----------------------------------------------------------------------+
> -| Why is the synchronize_rcu() on line 28 needed?                       |
> +| Why is the synchronize_rcu() on line 28 needed?                       |
>  +-----------------------------------------------------------------------+
>  | **Answer**:                                                           |
>  +-----------------------------------------------------------------------+
> @@ -244,7 +244,7 @@ their rights to reorder this code as follows:
>        16 }
>  
>  If an RCU reader fetches ``gp`` just after ``add_gp_buggy_optimized``
> -executes line 11, it will see garbage in the ``->a`` and ``->b`` fields.
> +executes line 11, it will see garbage in the ``->a`` and ``->b`` fields.
>  And this is but one of many ways in which compiler and hardware
>  optimizations could cause trouble. Therefore, we clearly need some way
>  to prevent the compiler and the CPU from reordering in this manner,
> @@ -279,11 +279,11 @@ shows an example of insertion:
>        15   return true;
>        16 }
>  
> -The rcu_assign_pointer() on line 13 is conceptually equivalent to a
> +The rcu_assign_pointer() on line 13 is conceptually equivalent to a
>  simple assignment statement, but also guarantees that its assignment
> -will happen after the two assignments in lines 11 and 12, similar to the
> +will happen after the two assignments in lines 11 and 12, similar to the
>  C11 ``memory_order_release`` store operation. It also prevents any
> -number of “interesting” compiler optimizations, for example, the use of
> +number of "interesting" compiler optimizations, for example, the use of
>  ``gp`` as a scratch location immediately preceding the assignment.
>  
>  +-----------------------------------------------------------------------+
> @@ -410,11 +410,11 @@ This process is implemented by remove_gp_synchronous():
>        15   return true;
>        16 }
>  
> -This function is straightforward, with line 13 waiting for a grace
> -period before line 14 frees the old data element. This waiting ensures
> -that readers will reach line 7 of do_something_gp() before the data
> +This function is straightforward, with line 13 waiting for a grace
> +period before line 14 frees the old data element. This waiting ensures
> +that readers will reach line 7 of do_something_gp() before the data
>  element referenced by ``p`` is freed. The rcu_access_pointer() on
> -line 6 is similar to rcu_dereference(), except that:
> +line 6 is similar to rcu_dereference(), except that:
>  
>  #. The value returned by rcu_access_pointer() cannot be
>     dereferenced. If you want to access the value pointed to as well as
> @@ -488,25 +488,25 @@ systems with more than one CPU:
>     section ends and the time that synchronize_rcu() returns. Without
>     this guarantee, a pre-existing RCU read-side critical section might
>     hold a reference to the newly removed ``struct foo`` after the
> -   kfree() on line 14 of remove_gp_synchronous().
> +   kfree() on line 14 of remove_gp_synchronous().
>  #. Each CPU that has an RCU read-side critical section that ends after
>     synchronize_rcu() returns is guaranteed to execute a full memory
>     barrier between the time that synchronize_rcu() begins and the
>     time that the RCU read-side critical section begins. Without this
>     guarantee, a later RCU read-side critical section running after the
> -   kfree() on line 14 of remove_gp_synchronous() might later run
> +   kfree() on line 14 of remove_gp_synchronous() might later run
>     do_something_gp() and find the newly deleted ``struct foo``.
>  #. If the task invoking synchronize_rcu() remains on a given CPU,
>     then that CPU is guaranteed to execute a full memory barrier sometime
>     during the execution of synchronize_rcu(). This guarantee ensures
> -   that the kfree() on line 14 of remove_gp_synchronous() really
> -   does execute after the removal on line 11.
> +   that the kfree() on line 14 of remove_gp_synchronous() really
> +   does execute after the removal on line 11.
>  #. If the task invoking synchronize_rcu() migrates among a group of
>     CPUs during that invocation, then each of the CPUs in that group is
>     guaranteed to execute a full memory barrier sometime during the
>     execution of synchronize_rcu(). This guarantee also ensures that
> -   the kfree() on line 14 of remove_gp_synchronous() really does
> -   execute after the removal on line 11, but also in the case where the
> +   the kfree() on line 14 of remove_gp_synchronous() really does
> +   execute after the removal on line 11, but also in the case where the
>     thread executing the synchronize_rcu() migrates in the meantime.
>  
>  +-----------------------------------------------------------------------+
> @@ -525,8 +525,8 @@ systems with more than one CPU:
>  | In other words, a given instance of synchronize_rcu() can avoid       |
>  | waiting on a given RCU read-side critical section only if it can      |
>  | prove that synchronize_rcu() started first.                           |
> -| A related question is “When rcu_read_lock() doesn't generate any      |
> -| code, why does it matter how it relates to a grace period?” The       |
> +| A related question is "When rcu_read_lock() doesn't generate any      |
> +| code, why does it matter how it relates to a grace period?" The       |
>  | answer is that it is not the relationship of rcu_read_lock()          |
>  | itself that is important, but rather the relationship of the code     |
>  | within the enclosed RCU read-side critical section to the code        |
> @@ -538,7 +538,7 @@ systems with more than one CPU:
>  | of any access following the grace period.                             |
>  |                                                                       |
>  | As of late 2016, mathematical models of RCU take this viewpoint, for  |
> -| example, see slides 62 and 63 of the `2016 LinuxCon                   |
> +| example, see slides 62 and 63 of the `2016 LinuxCon                   |
>  | EU <http://www2.rdrop.com/users/paulmck/scalability/paper/LinuxMM.201 |
>  | 6.10.04c.LCE.pdf>`__                                                  |
>  | presentation.                                                         |
> @@ -584,9 +584,9 @@ systems with more than one CPU:
>  |                                                                       |
>  | And similarly, without a memory barrier between the beginning of the  |
>  | grace period and the beginning of the RCU read-side critical section, |
> -| CPU 1 might end up accessing the freelist.                            |
> +| CPU 1 might end up accessing the freelist.                            |
>  |                                                                       |
> -| The “as if” rule of course applies, so that any implementation that   |
> +| The "as if" rule of course applies, so that any implementation that   |
>  | acts as if the appropriate memory barriers were in place is a correct |
>  | implementation. That said, it is much easier to fool yourself into    |
>  | believing that you have adhered to the as-if rule than it is to       |
> @@ -1002,7 +1002,7 @@ RCU implementation must abide by them. They therefore bear repeating:
>     ECC errors, NMIs, and other hardware events. Although a delay of more
>     than about 20 seconds can result in splats, the RCU implementation is
>     obligated to use algorithms that can tolerate extremely long delays,
> -   but where “extremely long” is not long enough to allow wrap-around
> +   but where "extremely long" is not long enough to allow wrap-around
>     when incrementing a 64-bit counter.
>  #. Both the compiler and the CPU can reorder memory accesses. Where it
>     matters, RCU must use compiler directives and memory-barrier
> @@ -1169,7 +1169,7 @@ Energy efficiency is a critical component of performance today, and
>  Linux-kernel RCU implementations must therefore avoid unnecessarily
>  awakening idle CPUs. I cannot claim that this requirement was
>  premeditated. In fact, I learned of it during a telephone conversation
> -in which I was given “frank and open” feedback on the importance of
> +in which I was given "frank and open" feedback on the importance of
>  energy efficiency in battery-powered systems and on specific
>  energy-efficiency shortcomings of the Linux-kernel RCU implementation.
>  In my experience, the battery-powered embedded community will consider
> @@ -1234,7 +1234,7 @@ requirements: A storm of synchronize_rcu_expedited() invocations on
>  4096 CPUs should at least make reasonable forward progress. In return
>  for its shorter latencies, synchronize_rcu_expedited() is permitted
>  to impose modest degradation of real-time latency on non-idle online
> -CPUs. Here, “modest” means roughly the same latency degradation as a
> +CPUs. Here, "modest" means roughly the same latency degradation as a
>  scheduling-clock interrupt.
>  
>  There are a number of situations where even
> @@ -1274,8 +1274,8 @@ be used in place of synchronize_rcu() as follows:
>        28 }
>  
>  A definition of ``struct foo`` is finally needed, and appears on
> -lines 1-5. The function remove_gp_cb() is passed to call_rcu()
> -on line 25, and will be invoked after the end of a subsequent grace
> +lines 1-5. The function remove_gp_cb() is passed to call_rcu()
> +on line 25, and will be invoked after the end of a subsequent grace
>  period. This gets the same effect as remove_gp_synchronous(), but
>  without forcing the updater to wait for a grace period to elapse. The
>  call_rcu() function may be used in a number of situations where
> @@ -1294,23 +1294,23 @@ threads or (in the Linux kernel) workqueues.
>  +-----------------------------------------------------------------------+
>  | **Quick Quiz**:                                                       |
>  +-----------------------------------------------------------------------+
> -| Why does line 19 use rcu_access_pointer()? After all,                 |
> -| call_rcu() on line 25 stores into the structure, which would          |
> +| Why does line 19 use rcu_access_pointer()? After all,                 |
> +| call_rcu() on line 25 stores into the structure, which would          |
>  | interact badly with concurrent insertions. Doesn't this mean that     |
>  | rcu_dereference() is required?                                        |
>  +-----------------------------------------------------------------------+
>  | **Answer**:                                                           |
>  +-----------------------------------------------------------------------+
> -| Presumably the ``->gp_lock`` acquired on line 18 excludes any         |
> +| Presumably the ``->gp_lock`` acquired on line 18 excludes any         |
>  | changes, including any insertions that rcu_dereference() would        |
>  | protect against. Therefore, any insertions will be delayed until      |
> -| after ``->gp_lock`` is released on line 25, which in turn means that  |
> +| after ``->gp_lock`` is released on line 25, which in turn means that  |
>  | rcu_access_pointer() suffices.                                        |
>  +-----------------------------------------------------------------------+
>  
>  However, all that remove_gp_cb() is doing is invoking kfree() on
>  the data element. This is a common idiom, and is supported by
> -kfree_rcu(), which allows “fire and forget” operation as shown
> +kfree_rcu(), which allows "fire and forget" operation as shown
>  below:
>  
>     ::
> @@ -1396,8 +1396,8 @@ may be used for this purpose, as shown below:
>        18   return true;
>        19 }
>  
> -On line 14, get_state_synchronize_rcu() obtains a “cookie” from RCU,
> -then line 15 carries out other tasks, and finally, line 16 returns
> +On line 14, get_state_synchronize_rcu() obtains a "cookie" from RCU,
> +then line 15 carries out other tasks, and finally, line 16 returns
>  immediately if a grace period has elapsed in the meantime, but otherwise
>  waits as required. The need for ``get_state_synchronize_rcu`` and
>  cond_synchronize_rcu() has appeared quite recently, so it is too
> @@ -1420,9 +1420,9 @@ example, an infinite loop in an RCU read-side critical section must by
>  definition prevent later grace periods from ever completing. For a more
>  involved example, consider a 64-CPU system built with
>  ``CONFIG_RCU_NOCB_CPU=y`` and booted with ``rcu_nocbs=1-63``, where
> -CPUs 1 through 63 spin in tight loops that invoke call_rcu(). Even
> +CPUs 1 through 63 spin in tight loops that invoke call_rcu(). Even
>  if these tight loops also contain calls to cond_resched() (thus
> -allowing grace periods to complete), CPU 0 simply will not be able to
> +allowing grace periods to complete), CPU 0 simply will not be able to
>  invoke callbacks as fast as the other 63 CPUs can register them, at
>  least not until the system runs out of memory. In both of these
>  examples, the Spiderman principle applies: With great power comes great
> @@ -1433,7 +1433,7 @@ callbacks.
>  RCU takes the following steps to encourage timely completion of grace
>  periods:
>  
> -#. If a grace period fails to complete within 100 milliseconds, RCU
> +#. If a grace period fails to complete within 100 milliseconds, RCU
>     causes future invocations of cond_resched() on the holdout CPUs
>     to provide an RCU quiescent state. RCU also causes those CPUs'
>     need_resched() invocations to return ``true``, but only after the
> @@ -1442,12 +1442,12 @@ periods:
>     indefinitely in the kernel without scheduling-clock interrupts, which
>     defeats the above need_resched() strategem. RCU will therefore
>     invoke resched_cpu() on any ``nohz_full`` CPUs still holding out
> -   after 109 milliseconds.
> +   after 109 milliseconds.
>  #. In kernels built with ``CONFIG_RCU_BOOST=y``, if a given task that
>     has been preempted within an RCU read-side critical section is
> -   holding out for more than 500 milliseconds, RCU will resort to
> +   holding out for more than 500 milliseconds, RCU will resort to
>     priority boosting.
> -#. If a CPU is still holding out 10 seconds into the grace period, RCU
> +#. If a CPU is still holding out 10 seconds into the grace period, RCU
>     will invoke resched_cpu() on it regardless of its ``nohz_full``
>     state.
>  
> @@ -1579,7 +1579,7 @@ period.
>  Software-Engineering Requirements
>  ---------------------------------
>  
> -Between Murphy's Law and “To err is human”, it is necessary to guard
> +Between Murphy's Law and "To err is human", it is necessary to guard
>  against mishaps and misuse:
>  
>  #. It is all too easy to forget to use rcu_read_lock() everywhere
> @@ -1626,7 +1626,7 @@ against mishaps and misuse:
>     `patch <https://lore.kernel.org/r/20100319013024.GA28456@Krystal>`__.
>  #. An infinite loop in an RCU read-side critical section will eventually
>     trigger an RCU CPU stall warning splat, with the duration of
> -   “eventually” being controlled by the ``RCU_CPU_STALL_TIMEOUT``
> +   "eventually" being controlled by the ``RCU_CPU_STALL_TIMEOUT``
>     ``Kconfig`` option, or, alternatively, by the
>     ``rcupdate.rcu_cpu_stall_timeout`` boot/sysfs parameter. However, RCU
>     is not obligated to produce this splat unless there is a grace period
> @@ -1704,7 +1704,7 @@ Configuration
>  
>  RCU's goal is automatic configuration, so that almost nobody needs to
>  worry about RCU's ``Kconfig`` options. And for almost all users, RCU
> -does in fact work well “out of the box.”
> +does in fact work well "out of the box."
>  
>  However, there are specialized use cases that are handled by kernel boot
>  parameters and ``Kconfig`` options. Unfortunately, the ``Kconfig``
> @@ -1733,7 +1733,7 @@ listings.
>  
>  RCU must therefore wait for a given CPU to actually come online before
>  it can allow itself to believe that the CPU actually exists. The
> -resulting “ghost CPUs” (which are never going to come online) cause a
> +resulting "ghost CPUs" (which are never going to come online) cause a
>  number of `interesting
>  complications <https://paulmck.livejournal.com/37494.html>`__.
>  
> @@ -1789,7 +1789,7 @@ normally.
>  | **Answer**:                                                           |
>  +-----------------------------------------------------------------------+
>  | Very carefully!                                                       |
> -| During the “dead zone” between the time that the scheduler spawns the |
> +| During the "dead zone" between the time that the scheduler spawns the |
>  | first task and the time that all of RCU's kthreads have been spawned, |
>  | all synchronous grace periods are handled by the expedited            |
>  | grace-period mechanism. At runtime, this expedited mechanism relies   |
> @@ -1824,7 +1824,7 @@ Some Linux-kernel architectures can enter an interrupt handler from
>  non-idle process context, and then just never leave it, instead
>  stealthily transitioning back to process context. This trick is
>  sometimes used to invoke system calls from inside the kernel. These
> -“half-interrupts” mean that RCU has to be very careful about how it
> +"half-interrupts" mean that RCU has to be very careful about how it
>  counts interrupt nesting levels. I learned of this requirement the hard
>  way during a rewrite of RCU's dyntick-idle code.
>  
> @@ -1921,7 +1921,7 @@ and go. It is of course illegal to use any RCU API member from an
>  offline CPU, with the exception of `SRCU <Sleepable RCU_>`__ read-side
>  critical sections. This requirement was present from day one in
>  DYNIX/ptx, but on the other hand, the Linux kernel's CPU-hotplug
> -implementation is “interesting.”
> +implementation is "interesting."
>  
>  The Linux-kernel CPU-hotplug implementation has notifiers that are used
>  to allow the various kernel subsystems (including RCU) to respond
> @@ -2268,7 +2268,7 @@ remain zero during all phases of grace-period processing, and that bit
>  happens to map to the bottom bit of the ``rcu_head`` structure's
>  ``->next`` field. RCU makes this guarantee as long as call_rcu() is
>  used to post the callback, as opposed to kfree_rcu() or some future
> -“lazy” variant of call_rcu() that might one day be created for
> +"lazy" variant of call_rcu() that might one day be created for
>  energy-efficiency purposes.
>  
>  That said, there are limits. RCU requires that the ``rcu_head``
> @@ -2281,7 +2281,7 @@ architecture provides only two-byte alignment, and thus acts as
>  alignment's least common denominator.
>  
>  The reason for reserving the bottom bit of pointers to ``rcu_head``
> -structures is to leave the door open to “lazy” callbacks whose
> +structures is to leave the door open to "lazy" callbacks whose
>  invocations can safely be deferred. Deferring invocation could
>  potentially have energy-efficiency benefits, but only if the rate of
>  non-lazy callbacks decreases significantly for some important workload.
> @@ -2354,8 +2354,8 @@ which in practice also means that RCU must have an aggressive
>  stress-test suite. This stress-test suite is called ``rcutorture``.
>  
>  Although the need for ``rcutorture`` was no surprise, the current
> -immense popularity of the Linux kernel is posing interesting—and perhaps
> -unprecedented—validation challenges. To see this, keep in mind that
> +immense popularity of the Linux kernel is posing interesting-and perhaps
> +unprecedented-validation challenges. To see this, keep in mind that
>  there are well over one billion instances of the Linux kernel running
>  today, given Android smartphones, Linux-powered televisions, and
>  servers. This number can be expected to increase sharply with the advent
> @@ -2399,7 +2399,7 @@ single flavor. The read-side API remains, and continues to disable
>  softirq and to be accounted for by lockdep. Much of the material in this
>  section is therefore strictly historical in nature.
>  
> -The softirq-disable (AKA “bottom-half”, hence the “_bh” abbreviations)
> +The softirq-disable (AKA "bottom-half", hence the "_bh" abbreviations)
>  flavor of RCU, or *RCU-bh*, was developed by Dipankar Sarma to provide a
>  flavor of RCU that could withstand the network-based denial-of-service
>  attacks researched by Robert Olsson. These attacks placed so much
> @@ -2458,7 +2458,7 @@ effect of also waiting for all pre-existing interrupt and NMI handlers.
>  However, there are legitimate preemptible-RCU implementations that do
>  not have this property, given that any point in the code outside of an
>  RCU read-side critical section can be a quiescent state. Therefore,
> -*RCU-sched* was created, which follows “classic” RCU in that an
> +*RCU-sched* was created, which follows "classic" RCU in that an
>  RCU-sched grace period waits for pre-existing interrupt and NMI
>  handlers. In kernels built with ``CONFIG_PREEMPTION=n``, the RCU and
>  RCU-sched APIs have identical implementations, while kernels built with
> @@ -2490,8 +2490,8 @@ and local_irq_restore(), and so on.
>  Sleepable RCU
>  ~~~~~~~~~~~~~
>  
> -For well over a decade, someone saying “I need to block within an RCU
> -read-side critical section” was a reliable indication that this someone
> +For well over a decade, someone saying "I need to block within an RCU
> +read-side critical section" was a reliable indication that this someone
>  did not understand RCU. After all, if you are always blocking in an RCU
>  read-side critical section, you can probably afford to use a
>  higher-overhead synchronization mechanism. However, that changed with
> @@ -2507,7 +2507,7 @@ this structure must be passed in to each SRCU function, for example,
>  structure. The key benefit of these domains is that a slow SRCU reader
>  in one domain does not delay an SRCU grace period in some other domain.
>  That said, one consequence of these domains is that read-side code must
> -pass a “cookie” from srcu_read_lock() to srcu_read_unlock(), for
> +pass a "cookie" from srcu_read_lock() to srcu_read_unlock(), for
>  example, as follows:
>  
>     ::
> @@ -2536,9 +2536,9 @@ period to elapse. For example, this results in a self-deadlock:
>         5 synchronize_srcu(&ss);
>         6 srcu_read_unlock(&ss, idx);
>  
> -However, if line 5 acquired a mutex that was held across a
> +However, if line 5 acquired a mutex that was held across a
>  synchronize_srcu() for domain ``ss``, deadlock would still be
> -possible. Furthermore, if line 5 acquired a mutex that was held across a
> +possible. Furthermore, if line 5 acquired a mutex that was held across a
>  synchronize_srcu() for some other domain ``ss1``, and if an
>  ``ss1``-domain SRCU read-side critical section acquired another mutex
>  that was held across as ``ss``-domain synchronize_srcu(), deadlock
> @@ -2557,7 +2557,7 @@ memory barrier.
>  Also unlike other RCU flavors, synchronize_srcu() may **not** be
>  invoked from CPU-hotplug notifiers, due to the fact that SRCU grace
>  periods make use of timers and the possibility of timers being
> -temporarily “stranded” on the outgoing CPU. This stranding of timers
> +temporarily "stranded" on the outgoing CPU. This stranding of timers
>  means that timers posted to the outgoing CPU will not fire until late in
>  the CPU-hotplug process. The problem is that if a notifier is waiting on
>  an SRCU grace period, that grace period is waiting on a timer, and that
> @@ -2573,7 +2573,7 @@ period has the side effect of expediting all prior grace periods that
>  have not yet completed. (But please note that this is a property of the
>  current implementation, not necessarily of future implementations.) In
>  addition, if SRCU has been idle for longer than the interval specified
> -by the ``srcutree.exp_holdoff`` kernel boot parameter (25 microseconds
> +by the ``srcutree.exp_holdoff`` kernel boot parameter (25 microseconds
>  by default), and if a synchronize_srcu() invocation ends this idle
>  period, that invocation will be automatically expedited.
>  
> @@ -2619,7 +2619,7 @@ from the cache, an SRCU grace period will be very likely to have elapsed.
>  Tasks RCU
>  ~~~~~~~~~
>  
> -Some forms of tracing use “trampolines” to handle the binary rewriting
> +Some forms of tracing use "trampolines" to handle the binary rewriting
>  required to install different types of probes. It would be good to be
>  able to free old trampolines, which sounds like a job for some form of
>  RCU. However, because it is necessary to be able to install a trace
> @@ -2687,7 +2687,7 @@ your architecture should also benefit from the
>  number of CPUs in a socket, NUMA node, or whatever. If the number of
>  CPUs is too large, use a fraction of the number of CPUs. If the number
>  of CPUs is a large prime number, well, that certainly is an
> -“interesting” architectural choice! More flexible arrangements might be
> +"interesting" architectural choice! More flexible arrangements might be
>  considered, but only if ``rcutree.rcu_fanout_leaf`` has proven
>  inadequate, and only if the inadequacy has been demonstrated by a
>  carefully run and realistic system-level workload.
> -- 
> 2.30.2
> 

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