| Message ID | 20090306132738.15896.2226.stgit@localhost.localdomain |
|---|---|
| State | Not Applicable, archived |
| Delegated to: | David Miller |
| Headers | show |
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; > } > } > -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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; > > } > > } > > -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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; } }
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(-) -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html