[PATCH 1/2] Doc: Fix missing whitespaces in RCU documentation.

[PATCH 1/2] Doc: Fix missing whitespaces in RCU documentation.

[Jesper Dangaard Brouer]

Trivial fix while reading through the RCU docs.

Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk>
---

 Documentation/RCU/rcu.txt |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/Documentation/RCU/rcu.txt b/Documentation/RCU/rcu.txt
index 95821a2..7aa2002 100644
--- a/Documentation/RCU/rcu.txt
+++ b/Documentation/RCU/rcu.txt
@@ -81,7 +81,7 @@ o	I hear that RCU needs work in order to support realtime kernels?
 	This work is largely completed.  Realtime-friendly RCU can be
 	enabled via the CONFIG_PREEMPT_RCU kernel configuration parameter.
 	However, work is in progress for enabling priority boosting of
-	preempted RCU read-side critical sections.This is needed if you
+	preempted RCU read-side critical sections.  This is needed if you
 	have CPU-bound realtime threads.
 
 o	Where can I find more information on RCU?

[PATCH 2/2] Doc: Fix wrong API example usage of call_rcu().

[Jesper Dangaard Brouer]

At some point the API of call_rcu() changed from three parameters
to two parameters, correct the documentation.

One confusing thing in RCU/listRCU.txt, which is NOT fixed in this patch,
is that no reason or explaination is given for using call_rcu() instead of
the normal synchronize_rcu() call.

Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk>
---

 Documentation/RCU/listRCU.txt |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/Documentation/RCU/listRCU.txt b/Documentation/RCU/listRCU.txt
index 1fd1753..4349c14 100644
--- a/Documentation/RCU/listRCU.txt
+++ b/Documentation/RCU/listRCU.txt
@@ -118,7 +118,7 @@ Following are the RCU equivalents for these two functions:
 		list_for_each_entry(e, list, list) {
 			if (!audit_compare_rule(rule, &e->rule)) {
 				list_del_rcu(&e->list);
-				call_rcu(&e->rcu, audit_free_rule, e);
+				call_rcu(&e->rcu, audit_free_rule);
 				return 0;
 			}
 		}
@@ -206,7 +206,7 @@ RCU ("read-copy update") its name.  The RCU code is as follows:
 				ne->rule.action = newaction;
 				ne->rule.file_count = newfield_count;
 				list_replace_rcu(e, ne);
-				call_rcu(&e->rcu, audit_free_rule, e);
+				call_rcu(&e->rcu, audit_free_rule);
 				return 0;
 			}
 		}
@@ -283,7 +283,7 @@ flag under the spinlock as follows:
 				list_del_rcu(&e->list);
 				e->deleted = 1;
 				spin_unlock(&e->lock);
-				call_rcu(&e->rcu, audit_free_rule, e);
+				call_rcu(&e->rcu, audit_free_rule);
 				return 0;
 			}
 		}

Re: [PATCH 1/2] Doc: Fix missing whitespaces in RCU documentation.

[Paul E. McKenney]

On Fri, Mar 06, 2009 at 02:27:33PM +0100, Jesper Dangaard Brouer wrote:
> Trivial fix while reading through the RCU docs.

Good eyes!

Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

> Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk>
> ---
> 
>  Documentation/RCU/rcu.txt |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/Documentation/RCU/rcu.txt b/Documentation/RCU/rcu.txt
> index 95821a2..7aa2002 100644
> --- a/Documentation/RCU/rcu.txt
> +++ b/Documentation/RCU/rcu.txt
> @@ -81,7 +81,7 @@ o	I hear that RCU needs work in order to support realtime kernels?
>  	This work is largely completed.  Realtime-friendly RCU can be
>  	enabled via the CONFIG_PREEMPT_RCU kernel configuration parameter.
>  	However, work is in progress for enabling priority boosting of
> -	preempted RCU read-side critical sections.This is needed if you
> +	preempted RCU read-side critical sections.  This is needed if you
>  	have CPU-bound realtime threads.
> 
>  o	Where can I find more information on RCU?
> 

Re: [PATCH 2/2] Doc: Fix wrong API example usage of call_rcu().

[Paul E. McKenney]

On Fri, Mar 06, 2009 at 02:27:38PM +0100, Jesper Dangaard Brouer wrote:
> At some point the API of call_rcu() changed from three parameters
> to two parameters, correct the documentation.
> 
> One confusing thing in RCU/listRCU.txt, which is NOT fixed in this patch,
> is that no reason or explaination is given for using call_rcu() instead of
> the normal synchronize_rcu() call.

Good catch!!!  Indeed, call_rcu() did take three arguments at one time,
like back in 2.5 days...

On the use of call_rcu() vs. synchronize_rcu(), the two possible reasons
called out in question 8 in Documentation/RCU/checklist.txt are:

1.	Update performance is important.

2.	Updaters cannot block.

I would welcome a patch to this file discussing this.

Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

> Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk>
> ---
> 
>  Documentation/RCU/listRCU.txt |    6 +++---
>  1 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/RCU/listRCU.txt b/Documentation/RCU/listRCU.txt
> index 1fd1753..4349c14 100644
> --- a/Documentation/RCU/listRCU.txt
> +++ b/Documentation/RCU/listRCU.txt
> @@ -118,7 +118,7 @@ Following are the RCU equivalents for these two functions:
>  		list_for_each_entry(e, list, list) {
>  			if (!audit_compare_rule(rule, &e->rule)) {
>  				list_del_rcu(&e->list);
> -				call_rcu(&e->rcu, audit_free_rule, e);
> +				call_rcu(&e->rcu, audit_free_rule);
>  				return 0;
>  			}
>  		}
> @@ -206,7 +206,7 @@ RCU ("read-copy update") its name.  The RCU code is as follows:
>  				ne->rule.action = newaction;
>  				ne->rule.file_count = newfield_count;
>  				list_replace_rcu(e, ne);
> -				call_rcu(&e->rcu, audit_free_rule, e);
> +				call_rcu(&e->rcu, audit_free_rule);
>  				return 0;
>  			}
>  		}
> @@ -283,7 +283,7 @@ flag under the spinlock as follows:
>  				list_del_rcu(&e->list);
>  				e->deleted = 1;
>  				spin_unlock(&e->lock);
> -				call_rcu(&e->rcu, audit_free_rule, e);
> +				call_rcu(&e->rcu, audit_free_rule);
>  				return 0;
>  			}
>  		}
> 

Re: [PATCH 2/2] Doc: Fix wrong API example usage of call_rcu().

[Paul E. McKenney]

On Fri, Mar 06, 2009 at 09:49:59PM -0800, Paul E. McKenney wrote:
> On Fri, Mar 06, 2009 at 02:27:38PM +0100, Jesper Dangaard Brouer wrote:
> > At some point the API of call_rcu() changed from three parameters
> > to two parameters, correct the documentation.
> > 
> > One confusing thing in RCU/listRCU.txt, which is NOT fixed in this patch,
> > is that no reason or explaination is given for using call_rcu() instead of
> > the normal synchronize_rcu() call.
> 
> Good catch!!!  Indeed, call_rcu() did take three arguments at one time,
> like back in 2.5 days...
> 
> On the use of call_rcu() vs. synchronize_rcu(), the two possible reasons
> called out in question 8 in Documentation/RCU/checklist.txt are:
> 
> 1.	Update performance is important.
> 
> 2.	Updaters cannot block.

And an important special case of #2 is when the update is being carried
out within an RCU read-side critical section, FWIW.

							Thanx, Paul

> I would welcome a patch to this file discussing this.
> 
> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> 
> > Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk>
> > ---
> > 
> >  Documentation/RCU/listRCU.txt |    6 +++---
> >  1 files changed, 3 insertions(+), 3 deletions(-)
> > 
> > diff --git a/Documentation/RCU/listRCU.txt b/Documentation/RCU/listRCU.txt
> > index 1fd1753..4349c14 100644
> > --- a/Documentation/RCU/listRCU.txt
> > +++ b/Documentation/RCU/listRCU.txt
> > @@ -118,7 +118,7 @@ Following are the RCU equivalents for these two functions:
> >  		list_for_each_entry(e, list, list) {
> >  			if (!audit_compare_rule(rule, &e->rule)) {
> >  				list_del_rcu(&e->list);
> > -				call_rcu(&e->rcu, audit_free_rule, e);
> > +				call_rcu(&e->rcu, audit_free_rule);
> >  				return 0;
> >  			}
> >  		}
> > @@ -206,7 +206,7 @@ RCU ("read-copy update") its name.  The RCU code is as follows:
> >  				ne->rule.action = newaction;
> >  				ne->rule.file_count = newfield_count;
> >  				list_replace_rcu(e, ne);
> > -				call_rcu(&e->rcu, audit_free_rule, e);
> > +				call_rcu(&e->rcu, audit_free_rule);
> >  				return 0;
> >  			}
> >  		}
> > @@ -283,7 +283,7 @@ flag under the spinlock as follows:
> >  				list_del_rcu(&e->list);
> >  				e->deleted = 1;
> >  				spin_unlock(&e->lock);
> > -				call_rcu(&e->rcu, audit_free_rule, e);
> > +				call_rcu(&e->rcu, audit_free_rule);
> >  				return 0;
> >  			}
> >  		}
> >