[PATCH v2 02/24] tools: docs: memory-model: fix references for some files

[PATCH v2 02/24] tools: docs: memory-model: fix references for some files

[Mauro Carvalho Chehab]

- The sysfs.txt file was converted to ReST and renamed;
- The control-dependencies.txt is not at
  Documentation/control-dependencies.txt. As it is at the
  same dir as the README file, which mentions it, just
  remove Documentation/.

With that, ./scripts/documentation-file-ref-check script
is now happy again for files under tools/.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
---
 tools/memory-model/Documentation/README       | 2 +-
 tools/memory-model/Documentation/ordering.txt | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/memory-model/Documentation/README b/tools/memory-model/Documentation/README
index 16177aaa9752..004969992bac 100644
--- a/tools/memory-model/Documentation/README
+++ b/tools/memory-model/Documentation/README
@@ -55,7 +55,7 @@ README
 Documentation/cheatsheet.txt
 	Quick-reference guide to the Linux-kernel memory model.
 
-Documentation/control-dependencies.txt
+control-dependencies.txt
 	A guide to preventing compiler optimizations from destroying
 	your control dependencies.
 
diff --git a/tools/memory-model/Documentation/ordering.txt b/tools/memory-model/Documentation/ordering.txt
index 3d020bed8585..629b19ae64a6 100644
--- a/tools/memory-model/Documentation/ordering.txt
+++ b/tools/memory-model/Documentation/ordering.txt
@@ -346,7 +346,7 @@ o	Accessing RCU-protected pointers via rcu_dereference()
 
 	If there is any significant processing of the pointer value
 	between the rcu_dereference() that returned it and a later
-	dereference(), please read Documentation/RCU/rcu_dereference.txt.
+	dereference(), please read Documentation/RCU/rcu_dereference.rst.
 
 It can also be quite helpful to review uses in the Linux kernel.
 
-- 
2.26.2

Re: [PATCH v2 02/24] tools: docs: memory-model: fix references for some files

[Paul E. McKenney]

On Tue, Oct 13, 2020 at 02:14:29PM +0200, Mauro Carvalho Chehab wrote:
> - The sysfs.txt file was converted to ReST and renamed;
> - The control-dependencies.txt is not at
>   Documentation/control-dependencies.txt. As it is at the
>   same dir as the README file, which mentions it, just
>   remove Documentation/.
> 
> With that, ./scripts/documentation-file-ref-check script
> is now happy again for files under tools/.
> 
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

Queued for review and testing, likely target v5.11.

							Thanx, Paul

> ---
>  tools/memory-model/Documentation/README       | 2 +-
>  tools/memory-model/Documentation/ordering.txt | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/memory-model/Documentation/README b/tools/memory-model/Documentation/README
> index 16177aaa9752..004969992bac 100644
> --- a/tools/memory-model/Documentation/README
> +++ b/tools/memory-model/Documentation/README
> @@ -55,7 +55,7 @@ README
>  Documentation/cheatsheet.txt
>  	Quick-reference guide to the Linux-kernel memory model.
>  
> -Documentation/control-dependencies.txt
> +control-dependencies.txt
>  	A guide to preventing compiler optimizations from destroying
>  	your control dependencies.
>  
> diff --git a/tools/memory-model/Documentation/ordering.txt b/tools/memory-model/Documentation/ordering.txt
> index 3d020bed8585..629b19ae64a6 100644
> --- a/tools/memory-model/Documentation/ordering.txt
> +++ b/tools/memory-model/Documentation/ordering.txt
> @@ -346,7 +346,7 @@ o	Accessing RCU-protected pointers via rcu_dereference()
>  
>  	If there is any significant processing of the pointer value
>  	between the rcu_dereference() that returned it and a later
> -	dereference(), please read Documentation/RCU/rcu_dereference.txt.
> +	dereference(), please read Documentation/RCU/rcu_dereference.rst.
>  
>  It can also be quite helpful to review uses in the Linux kernel.
>  
> -- 
> 2.26.2
> 

Re: [PATCH v2 02/24] tools: docs: memory-model: fix references for some files

[Alan Stern]

On Tue, Oct 13, 2020 at 09:33:54AM -0700, Paul E. McKenney wrote:
> On Tue, Oct 13, 2020 at 02:14:29PM +0200, Mauro Carvalho Chehab wrote:
> > - The sysfs.txt file was converted to ReST and renamed;
> > - The control-dependencies.txt is not at
> >   Documentation/control-dependencies.txt. As it is at the
> >   same dir as the README file, which mentions it, just
> >   remove Documentation/.
> > 
> > With that, ./scripts/documentation-file-ref-check script
> > is now happy again for files under tools/.
> > 
> > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
> 
> Queued for review and testing, likely target v5.11.

Instead of changing the path in the README reference, shouldn't 
tools/memory-model/control-dependencies.txt be moved to its proper 
position in .../Documentation?

Alan Stern

Re: [PATCH v2 02/24] tools: docs: memory-model: fix references for some files

[Paul E. McKenney]

On Tue, Oct 13, 2020 at 12:38:36PM -0400, Alan Stern wrote:
> On Tue, Oct 13, 2020 at 09:33:54AM -0700, Paul E. McKenney wrote:
> > On Tue, Oct 13, 2020 at 02:14:29PM +0200, Mauro Carvalho Chehab wrote:
> > > - The sysfs.txt file was converted to ReST and renamed;
> > > - The control-dependencies.txt is not at
> > >   Documentation/control-dependencies.txt. As it is at the
> > >   same dir as the README file, which mentions it, just
> > >   remove Documentation/.
> > > 
> > > With that, ./scripts/documentation-file-ref-check script
> > > is now happy again for files under tools/.
> > > 
> > > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
> > 
> > Queued for review and testing, likely target v5.11.
> 
> Instead of changing the path in the README reference, shouldn't 
> tools/memory-model/control-dependencies.txt be moved to its proper 
> position in .../Documentation?

You are of course quite right.  My thought is to let Mauro go ahead,
given his short deadline.  We can then make this "git mv" change once
v5.10-rc1 comes out, given that it should have Mauro's patches.  I have
added a reminder to my calendar.

							Thanx, Paul

Re: [PATCH v2 02/24] tools: docs: memory-model: fix references for some files

[Mauro Carvalho Chehab]

Em Tue, 13 Oct 2020 18:58:40 -0700
"Paul E. McKenney" <paulmck@kernel.org> escreveu:

> On Tue, Oct 13, 2020 at 12:38:36PM -0400, Alan Stern wrote:
> > On Tue, Oct 13, 2020 at 09:33:54AM -0700, Paul E. McKenney wrote:  
> > > On Tue, Oct 13, 2020 at 02:14:29PM +0200, Mauro Carvalho Chehab wrote:  
> > > > - The sysfs.txt file was converted to ReST and renamed;
> > > > - The control-dependencies.txt is not at
> > > >   Documentation/control-dependencies.txt. As it is at the
> > > >   same dir as the README file, which mentions it, just
> > > >   remove Documentation/.
> > > > 
> > > > With that, ./scripts/documentation-file-ref-check script
> > > > is now happy again for files under tools/.
> > > > 
> > > > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>  
> > > 
> > > Queued for review and testing, likely target v5.11.  
> > 
> > Instead of changing the path in the README reference, shouldn't 
> > tools/memory-model/control-dependencies.txt be moved to its proper 
> > position in .../Documentation?  
> 
> You are of course quite right.  My thought is to let Mauro go ahead,
> given his short deadline.  We can then make this "git mv" change once
> v5.10-rc1 comes out, given that it should have Mauro's patches.  I have
> added a reminder to my calendar.

Sounds like a plan to me.


If it helps on 5.11 plans, converting this file to ReST format is quite
trivial: it just needs to use "::" for C/asm code literal blocks, and 
to replace "(*) " by something that matches ReST syntax for lists,
like "(#) " or just "* ":

	https://docutils.sourceforge.io/docs/ref/rst/restructuredtext.html#bullet-lists

See enclosed.

Thanks,
Mauro

[PATCH] convert control-dependencies.rst to ReST

- Mark literal blocks as such;
- Use a numbered list at the summary.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

diff --git a/tools/memory-model/Documentation/control-dependencies.rst b/tools/memory-model/Documentation/control-dependencies.rst
index 366520cac937..52dc6a5bc173 100644
--- a/tools/memory-model/Documentation/control-dependencies.rst
+++ b/tools/memory-model/Documentation/control-dependencies.rst
@@ -7,7 +7,7 @@ the compiler's ignorance from breaking your code.
 
 A load-load control dependency requires a full read memory barrier, not
 simply a data dependency barrier to make it work correctly.  Consider the
-following bit of code:
+following bit of code::
 
 	q = READ_ONCE(a);
 	if (q) {
@@ -19,7 +19,7 @@ This will not have the desired effect because there is no actual data
 dependency, but rather a control dependency that the CPU may short-circuit
 by attempting to predict the outcome in advance, so that other CPUs see
 the load from b as having happened before the load from a.  In such a
-case what's actually required is:
+case what's actually required is::
 
 	q = READ_ONCE(a);
 	if (q) {
@@ -28,7 +28,7 @@ case what's actually required is:
 	}
 
 However, stores are not speculated.  This means that ordering -is- provided
-for load-store control dependencies, as in the following example:
+for load-store control dependencies, as in the following example::
 
 	q = READ_ONCE(a);
 	if (q) {
@@ -45,7 +45,7 @@ or, worse yet, convert the store into a check followed by a store.
 Worse yet, if the compiler is able to prove (say) that the value of
 variable "a" is always non-zero, it would be well within its rights
 to optimize the original example by eliminating the "if" statement
-as follows:
+as follows::
 
 	q = a;
 	b = 1;  /* BUG: Compiler and CPU can both reorder!!! */
@@ -53,7 +53,7 @@ as follows:
 So don't leave out either the READ_ONCE() or the WRITE_ONCE().
 
 It is tempting to try to enforce ordering on identical stores on both
-branches of the "if" statement as follows:
+branches of the "if" statement as follows::
 
 	q = READ_ONCE(a);
 	if (q) {
@@ -67,7 +67,7 @@ branches of the "if" statement as follows:
 	}
 
 Unfortunately, current compilers will transform this as follows at high
-optimization levels:
+optimization levels::
 
 	q = READ_ONCE(a);
 	barrier();
@@ -85,7 +85,7 @@ Now there is no conditional between the load from "a" and the store to
 The conditional is absolutely required, and must be present in the
 assembly code even after all compiler optimizations have been applied.
 Therefore, if you need ordering in this example, you need explicit
-memory barriers, for example, smp_store_release():
+memory barriers, for example, smp_store_release()::
 
 	q = READ_ONCE(a);
 	if (q) {
@@ -97,7 +97,7 @@ memory barriers, for example, smp_store_release():
 	}
 
 In contrast, without explicit memory barriers, two-legged-if control
-ordering is guaranteed only when the stores differ, for example:
+ordering is guaranteed only when the stores differ, for example::
 
 	q = READ_ONCE(a);
 	if (q) {
@@ -113,7 +113,7 @@ proving the value of "a".
 
 In addition, you need to be careful what you do with the local variable "q",
 otherwise the compiler might be able to guess the value and again remove
-the needed conditional.  For example:
+the needed conditional.  For example::
 
 	q = READ_ONCE(a);
 	if (q % MAX) {
@@ -126,7 +126,7 @@ the needed conditional.  For example:
 
 If MAX is defined to be 1, then the compiler knows that (q % MAX) is
 equal to zero, in which case the compiler is within its rights to
-transform the above code into the following:
+transform the above code into the following::
 
 	q = READ_ONCE(a);
 	WRITE_ONCE(b, 2);
@@ -137,7 +137,7 @@ between the load from variable "a" and the store to variable "b".  It is
 tempting to add a barrier(), but this does not help.  The conditional
 is gone, and the barrier won't bring it back.  Therefore, if you are
 relying on this ordering, you should make sure that MAX is greater than
-one, perhaps as follows:
+one, perhaps as follows::
 
 	q = READ_ONCE(a);
 	BUILD_BUG_ON(MAX <= 1); /* Order load from a with store to b. */
@@ -154,7 +154,7 @@ identical, as noted earlier, the compiler could pull this store outside
 of the 'if' statement.
 
 You must also be careful not to rely too much on boolean short-circuit
-evaluation.  Consider this example:
+evaluation.  Consider this example::
 
 	q = READ_ONCE(a);
 	if (q || 1 > 0)
@@ -162,7 +162,7 @@ evaluation.  Consider this example:
 
 Because the first condition cannot fault and the second condition is
 always true, the compiler can transform this example as following,
-defeating control dependency:
+defeating control dependency::
 
 	q = READ_ONCE(a);
 	WRITE_ONCE(b, 1);
@@ -174,7 +174,7 @@ the compiler to use the results.
 
 In addition, control dependencies apply only to the then-clause and
 else-clause of the if-statement in question.  In particular, it does
-not necessarily apply to code following the if-statement:
+not necessarily apply to code following the if-statement::
 
 	q = READ_ONCE(a);
 	if (q) {
@@ -189,7 +189,7 @@ compiler cannot reorder volatile accesses and also cannot reorder
 the writes to "b" with the condition.  Unfortunately for this line
 of reasoning, the compiler might compile the two writes to "b" as
 conditional-move instructions, as in this fanciful pseudo-assembly
-language:
+language::
 
 	ld r1,a
 	cmp r1,$0
@@ -213,14 +213,14 @@ for more information.
 
 In summary:
 
-  (*) Control dependencies can order prior loads against later stores.
+  (#) Control dependencies can order prior loads against later stores.
       However, they do -not- guarantee any other sort of ordering:
       Not prior loads against later loads, nor prior stores against
       later anything.  If you need these other forms of ordering,
       use smp_rmb(), smp_wmb(), or, in the case of prior stores and
       later loads, smp_mb().
 
-  (*) If both legs of the "if" statement begin with identical stores to
+  (#) If both legs of the "if" statement begin with identical stores to
       the same variable, then those stores must be ordered, either by
       preceding both of them with smp_mb() or by using smp_store_release()
       to carry out the stores.  Please note that it is -not- sufficient
@@ -229,28 +229,28 @@ In summary:
       destroy the control dependency while respecting the letter of the
       barrier() law.
 
-  (*) Control dependencies require at least one run-time conditional
+  (#) Control dependencies require at least one run-time conditional
       between the prior load and the subsequent store, and this
       conditional must involve the prior load.  If the compiler is able
       to optimize the conditional away, it will have also optimized
       away the ordering.  Careful use of READ_ONCE() and WRITE_ONCE()
       can help to preserve the needed conditional.
 
-  (*) Control dependencies require that the compiler avoid reordering the
+  (#) Control dependencies require that the compiler avoid reordering the
       dependency into nonexistence.  Careful use of READ_ONCE() or
       atomic{,64}_read() can help to preserve your control dependency.
       Please see the COMPILER BARRIER section for more information.
 
-  (*) Control dependencies apply only to the then-clause and else-clause
+  (#) Control dependencies apply only to the then-clause and else-clause
       of the if-statement containing the control dependency, including
       any functions that these two clauses call.  Control dependencies
       do -not- apply to code following the if-statement containing the
       control dependency.
 
-  (*) Control dependencies pair normally with other types of barriers.
+  (#) Control dependencies pair normally with other types of barriers.
 
-  (*) Control dependencies do -not- provide multicopy atomicity.  If you
+  (#) Control dependencies do -not- provide multicopy atomicity.  If you
       need all the CPUs to see a given store at the same time, use smp_mb().
 
-  (*) Compilers do not understand control dependencies.  It is therefore
+  (#) Compilers do not understand control dependencies.  It is therefore
       your job to ensure that they do not break your code.

Re: [PATCH v2 02/24] tools: docs: memory-model: fix references for some files

[Akira Yokosawa]

On Wed, 14 Oct 2020 09:56:03 +0200, Mauro Carvalho Chehab wrote:
> Em Tue, 13 Oct 2020 18:58:40 -0700
> "Paul E. McKenney" <paulmck@kernel.org> escreveu:
> 
>> On Tue, Oct 13, 2020 at 12:38:36PM -0400, Alan Stern wrote:
>>> On Tue, Oct 13, 2020 at 09:33:54AM -0700, Paul E. McKenney wrote:  
>>>> On Tue, Oct 13, 2020 at 02:14:29PM +0200, Mauro Carvalho Chehab wrote:  
>>>>> - The sysfs.txt file was converted to ReST and renamed;
>>>>> - The control-dependencies.txt is not at
>>>>>   Documentation/control-dependencies.txt. As it is at the
>>>>>   same dir as the README file, which mentions it, just
>>>>>   remove Documentation/.
>>>>>
>>>>> With that, ./scripts/documentation-file-ref-check script
>>>>> is now happy again for files under tools/.
>>>>>
>>>>> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>  
>>>>
>>>> Queued for review and testing, likely target v5.11.  
>>>
>>> Instead of changing the path in the README reference, shouldn't 
>>> tools/memory-model/control-dependencies.txt be moved to its proper 
>>> position in .../Documentation?  
>>
>> You are of course quite right.  My thought is to let Mauro go ahead,
>> given his short deadline.  We can then make this "git mv" change once
>> v5.10-rc1 comes out, given that it should have Mauro's patches.  I have
>> added a reminder to my calendar.
> 
> Sounds like a plan to me.
> 
> 
> If it helps on 5.11 plans, converting this file to ReST format is quite
> trivial: it just needs to use "::" for C/asm code literal blocks, and 
> to replace "(*) " by something that matches ReST syntax for lists,
> like "(#) " or just "* ":
> 
> 	https://docutils.sourceforge.io/docs/ref/rst/restructuredtext.html#bullet-lists
> 
> See enclosed.

I'm afraid conversion of LKMM documents to ReST is unlikely to happen
any time soon.
It should wait until such time comes when the auto markup tools become
clever enough and .rst files looks exactly the same as plain .txt files.

Am I asking too much? :-)

        Thanks, Akira

> 
> Thanks,
> Mauro
> 
> [PATCH] convert control-dependencies.rst to ReST
> 

[snip]

Re: [PATCH v2 02/24] tools: docs: memory-model: fix references for some files

[Mauro Carvalho Chehab]

Em Wed, 14 Oct 2020 23:14:00 +0900
Akira Yokosawa <akiyks@gmail.com> escreveu:

> On Wed, 14 Oct 2020 09:56:03 +0200, Mauro Carvalho Chehab wrote:
> > Em Tue, 13 Oct 2020 18:58:40 -0700
> > "Paul E. McKenney" <paulmck@kernel.org> escreveu:
> >   
> >> On Tue, Oct 13, 2020 at 12:38:36PM -0400, Alan Stern wrote:  
> >>> On Tue, Oct 13, 2020 at 09:33:54AM -0700, Paul E. McKenney wrote:    
> >>>> On Tue, Oct 13, 2020 at 02:14:29PM +0200, Mauro Carvalho Chehab wrote:    
> >>>>> - The sysfs.txt file was converted to ReST and renamed;
> >>>>> - The control-dependencies.txt is not at
> >>>>>   Documentation/control-dependencies.txt. As it is at the
> >>>>>   same dir as the README file, which mentions it, just
> >>>>>   remove Documentation/.
> >>>>>
> >>>>> With that, ./scripts/documentation-file-ref-check script
> >>>>> is now happy again for files under tools/.
> >>>>>
> >>>>> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>    
> >>>>
> >>>> Queued for review and testing, likely target v5.11.    
> >>>
> >>> Instead of changing the path in the README reference, shouldn't 
> >>> tools/memory-model/control-dependencies.txt be moved to its proper 
> >>> position in .../Documentation?    
> >>
> >> You are of course quite right.  My thought is to let Mauro go ahead,
> >> given his short deadline.  We can then make this "git mv" change once
> >> v5.10-rc1 comes out, given that it should have Mauro's patches.  I have
> >> added a reminder to my calendar.  
> > 
> > Sounds like a plan to me.
> > 
> > 
> > If it helps on 5.11 plans, converting this file to ReST format is quite
> > trivial: it just needs to use "::" for C/asm code literal blocks, and 
> > to replace "(*) " by something that matches ReST syntax for lists,
> > like "(#) " or just "* ":
> > 
> > 	https://docutils.sourceforge.io/docs/ref/rst/restructuredtext.html#bullet-lists
> > 
> > See enclosed.  
> 
> I'm afraid conversion of LKMM documents to ReST is unlikely to happen
> any time soon.
> It should wait until such time comes when the auto markup tools become
> clever enough and .rst files looks exactly the same as plain .txt files.
> 
> Am I asking too much? :-)
> 
>         Thanks, Akira

Yes :-)

	$ git log --author akiyks@gmail.com Documentation/sphinx
	$

The auto markup tools don't write themselves alone. Someone needs 
to write them and test if no regressions will happen with the existing
documents.

-

That's said, I suspect that one of the hardest things for something
like that to be possible is to be able to distinguish something
like:

	(some text)

From something like:

	/* some C code snippet or bash script, or other literal block */

So, at least "::" (or some other markup replacing it) is needed.

If you have some bright idea about how to implement it, feel free
to contribute with patches.

Thanks,
Mauro

Re: [PATCH v2 02/24] tools: docs: memory-model: fix references for some files

[Paul E. McKenney]

On Tue, Oct 13, 2020 at 06:58:40PM -0700, Paul E. McKenney wrote:
> On Tue, Oct 13, 2020 at 12:38:36PM -0400, Alan Stern wrote:
> > On Tue, Oct 13, 2020 at 09:33:54AM -0700, Paul E. McKenney wrote:
> > > On Tue, Oct 13, 2020 at 02:14:29PM +0200, Mauro Carvalho Chehab wrote:
> > > > - The sysfs.txt file was converted to ReST and renamed;
> > > > - The control-dependencies.txt is not at
> > > >   Documentation/control-dependencies.txt. As it is at the
> > > >   same dir as the README file, which mentions it, just
> > > >   remove Documentation/.
> > > > 
> > > > With that, ./scripts/documentation-file-ref-check script
> > > > is now happy again for files under tools/.
> > > > 
> > > > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
> > > 
> > > Queued for review and testing, likely target v5.11.
> > 
> > Instead of changing the path in the README reference, shouldn't 
> > tools/memory-model/control-dependencies.txt be moved to its proper 
> > position in .../Documentation?
> 
> You are of course quite right.  My thought is to let Mauro go ahead,
> given his short deadline.  We can then make this "git mv" change once
> v5.10-rc1 comes out, given that it should have Mauro's patches.  I have
> added a reminder to my calendar.

Except that I cannot find a commit where control-dependencies.txt is
in tools/memory-model.  And this file is not yet in mainline, but
only in -rcu and -next.  In both places, it is here:

	tools/memory-model/Documentation/control-dependencies.txt

Mauro, to what commit in what tree are you applying this patch?

							Thanx, Paul

Re: [PATCH v2 02/24] tools: docs: memory-model: fix references for some files

[Mauro Carvalho Chehab]

Hi Paul,

Em Wed, 14 Oct 2020 11:57:20 -0700
"Paul E. McKenney" <paulmck@kernel.org> escreveu:

> On Tue, Oct 13, 2020 at 06:58:40PM -0700, Paul E. McKenney wrote:
> > On Tue, Oct 13, 2020 at 12:38:36PM -0400, Alan Stern wrote:  
> > > On Tue, Oct 13, 2020 at 09:33:54AM -0700, Paul E. McKenney wrote:  
> > > > On Tue, Oct 13, 2020 at 02:14:29PM +0200, Mauro Carvalho Chehab wrote:  
> > > > > - The sysfs.txt file was converted to ReST and renamed;
> > > > > - The control-dependencies.txt is not at
> > > > >   Documentation/control-dependencies.txt. As it is at the
> > > > >   same dir as the README file, which mentions it, just
> > > > >   remove Documentation/.
> > > > > 
> > > > > With that, ./scripts/documentation-file-ref-check script
> > > > > is now happy again for files under tools/.
> > > > > 
> > > > > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>  
> > > > 
> > > > Queued for review and testing, likely target v5.11.  
> > > 
> > > Instead of changing the path in the README reference, shouldn't 
> > > tools/memory-model/control-dependencies.txt be moved to its proper 
> > > position in .../Documentation?  
> > 
> > You are of course quite right.  My thought is to let Mauro go ahead,
> > given his short deadline. 

I guess there might be some misunderstanding here. My fault. The plan
is to have zero doc warnings for 5.10[1].

In order to get there, The patches for it were split on two series,
both for 5.10:

- The /80 series with patches that already applies on the top of master;
- This /24 patch series, which depends on trees that weren't merged
  upstream yet (back on Oct, 13). Those applies on the top of
  next-20201013.

I'm intending to submit later today (after next-20201015) a PR with 
patches from the /80 series.

The remaining ones should be sent as a late pull request by the end 
of the merge window, if the patch that caused the issue gets merged
for 5.10. That's the case of this patch.


[1] With Sphinx < 3. Sphinx 3 and above brings some additional
    warnings that depends on a fix at the toolset. The fixup patches
    for Sphinx were proposed yesterday by the Sphinx maintainer
    of the C domain parser. More details can be seen here:

	https://github.com/sphinx-doc/sphinx/pull/8313


> >  We can then make this "git mv" change once
> > v5.10-rc1 comes out, given that it should have Mauro's patches.  I have
> > added a reminder to my calendar.  
> 
> Except that I cannot find a commit where control-dependencies.txt is
> in tools/memory-model.  And this file is not yet in mainline, but
> only in -rcu and -next.  In both places, it is here:
> 
> 	tools/memory-model/Documentation/control-dependencies.txt
> 
> Mauro, to what commit in what tree are you applying this patch?

This is against next-20201013. The specific commit adding
README and control-dependencies.txt is this one:

commit d34a972f67252457158122e5ba7a0ce5ece62067
Author:     Paul E. McKenney <paulmck@kernel.org>
AuthorDate: Tue Aug 11 11:27:33 2020 -0700
Commit:     Paul E. McKenney <paulmck@kernel.org>
CommitDate: Sun Oct 4 17:21:31 2020 -0700

    tools/memory-model: Document categories of ordering primitives
    
    The Linux kernel has a number of categories of ordering primitives, which
    are recorded in the LKMM implementation and hinted at by cheatsheet.txt.
    But there is no overview of these categories, and such an overview
    is needed in order to understand multithreaded LKMM litmus tests.
    This commit therefore adds an ordering.txt as well as extracting a
    control-dependencies.txt from memory-barriers.txt.  It also updates the
    README file.
    
    [ paulmck: Apply Akira Yokosawa file-placement feedback. ]
    [ paulmck:  Apply Alan Stern feedback. ]
    Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

Btw, after re-checking the patch, I would drop this hunk:

diff --git a/tools/memory-model/Documentation/README b/tools/memory-model/Documentation/README
index 16177aaa9752..004969992bac 100644
--- a/tools/memory-model/Documentation/README
+++ b/tools/memory-model/Documentation/README
@@ -55,7 +55,7 @@ README
 Documentation/cheatsheet.txt
 	Quick-reference guide to the Linux-kernel memory model.
 
-Documentation/control-dependencies.txt
+control-dependencies.txt
 	A guide to preventing compiler optimizations from destroying
 	your control dependencies.

The ./scripts/documentation-file-ref-check doesn't complain about
broken references for Documentation/ files outside the main
docs dir. So, this hunk is not really needed to fix warnings with
5.10. Besides that, there are other references to those files:

	$ git grep Documentation tools/memory-model/Documentation/README
	tools/memory-model/Documentation/README:tools/memory-model/Documentation directory.  It has been said that at
	tools/memory-model/Documentation/README:Documentation/cheatsheet.txt
	tools/memory-model/Documentation/README:Documentation/control-dependencies.txt
	tools/memory-model/Documentation/README:Documentation/explanation.txt
	tools/memory-model/Documentation/README:Documentation/litmus-tests.txt
	tools/memory-model/Documentation/README:Documentation/ordering.txt
	tools/memory-model/Documentation/README:Documentation/recipes.txt
	tools/memory-model/Documentation/README:Documentation/references.txt
	tools/memory-model/Documentation/README:Documentation/simple.txt

That also refer to the files inside tools/memory-model/Documentation/.
So, they should ether all be replaced to just the file name without
the directory (IMHO, that makes more sense) or kept as-is.

In any case, for 5.10, all we need is to fix this reference:

	Documentation/RCU/rcu_dereference.txt -> Documentation/RCU/rcu_dereference.rst

Also, the patch description is wrong. I suspect that, when this patch
was originally written, there were more hunks being touched, but
fixes for everything else were already merged. So, the only thing that
is left is the above change.

It follows a new version. feel free to either pick (or merge) this one at 
the same tree as tools/memory-model/Documentation/ordering.txt if you
think that this works best for you.

Otherwise, I'll keep this on my -next tree together with this series,
aiming to submit by the end of the merge window, if ordering.txt gets
merged for 5.10.

Thanks,
Mauro

[PATCH v2.1 02/24] tools/memory-model: fix a broken doc reference

Documentation/RCU/rcu_dereference.txt -> Documentation/RCU/rcu_dereference.rst

Fixes: d34a972f6725 ("tools/memory-model: Document categories of ordering primitives")
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

diff --git a/tools/memory-model/Documentation/ordering.txt b/tools/memory-model/Documentation/ordering.txt
index 3d020bed8585..629b19ae64a6 100644
--- a/tools/memory-model/Documentation/ordering.txt
+++ b/tools/memory-model/Documentation/ordering.txt
@@ -346,7 +346,7 @@ o	Accessing RCU-protected pointers via rcu_dereference()
 
 	If there is any significant processing of the pointer value
 	between the rcu_dereference() that returned it and a later
-	dereference(), please read Documentation/RCU/rcu_dereference.txt.
+	dereference(), please read Documentation/RCU/rcu_dereference.rst.
 
 It can also be quite helpful to review uses in the Linux kernel.
 

Re: [PATCH v2 02/24] tools: docs: memory-model: fix references for some files

[Peter Zijlstra]

On Thu, Oct 15, 2020 at 07:15:18AM +0200, Mauro Carvalho Chehab wrote:
> I guess there might be some misunderstanding here. My fault. The plan
> is to have zero doc warnings for 5.10[1].

I'd be glad to help and convert all the documentation under my
maintainership to .txt files for you.