| Message ID | 1304256126-26015-45-git-send-email-paulmck@linux.vnet.ibm.com |
|---|---|
| State | New |
| Headers | show |
On Sun, May 01, 2011 at 06:21:25AM -0700, Paul E. McKenney wrote: > From: Lai Jiangshan <laijs@cn.fujitsu.com> > > There is no callback of this module maybe queued > since we use kfree_rcu(), we can safely remove the rcu_barrier(). > > Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> > Acked-by: David S. Miller <davem@davemloft.net> > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > --- > net/sched/act_police.c | 1 - > 1 files changed, 0 insertions(+), 1 deletions(-) > > diff --git a/net/sched/act_police.c b/net/sched/act_police.c > index d6bcd64..b3b9b32 100644 > --- a/net/sched/act_police.c > +++ b/net/sched/act_police.c > @@ -396,7 +396,6 @@ static void __exit > police_cleanup_module(void) > { > tcf_unregister_action(&act_police_ops); > - rcu_barrier(); /* Wait for completion of call_rcu()'s (tcf_police_free_rcu) */ > } Very nice side-effect of having common callback code. Seems worth doing a review of other callers of rcu_barrier as well, to see if they still need to do so. - Josh Triplett
On Sun, May 01, 2011 at 08:59:35AM -0700, Josh Triplett wrote: > On Sun, May 01, 2011 at 06:21:25AM -0700, Paul E. McKenney wrote: > > From: Lai Jiangshan <laijs@cn.fujitsu.com> > > > > There is no callback of this module maybe queued > > since we use kfree_rcu(), we can safely remove the rcu_barrier(). > > > > Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> > > Acked-by: David S. Miller <davem@davemloft.net> > > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > > --- > > net/sched/act_police.c | 1 - > > 1 files changed, 0 insertions(+), 1 deletions(-) > > > > diff --git a/net/sched/act_police.c b/net/sched/act_police.c > > index d6bcd64..b3b9b32 100644 > > --- a/net/sched/act_police.c > > +++ b/net/sched/act_police.c > > @@ -396,7 +396,6 @@ static void __exit > > police_cleanup_module(void) > > { > > tcf_unregister_action(&act_police_ops); > > - rcu_barrier(); /* Wait for completion of call_rcu()'s (tcf_police_free_rcu) */ > > } > > Very nice side-effect of having common callback code. Seems worth doing > a review of other callers of rcu_barrier as well, to see if they still > need to do so. Agreed, and good point on the review. /me wonders how this review could be automated... Thanx, Paul
On Mon, May 02, 2011 at 01:36:18AM -0700, Paul E. McKenney wrote: > On Sun, May 01, 2011 at 08:59:35AM -0700, Josh Triplett wrote: > > On Sun, May 01, 2011 at 06:21:25AM -0700, Paul E. McKenney wrote: > > > From: Lai Jiangshan <laijs@cn.fujitsu.com> > > > > > > There is no callback of this module maybe queued > > > since we use kfree_rcu(), we can safely remove the rcu_barrier(). > > > > > > Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> > > > Acked-by: David S. Miller <davem@davemloft.net> > > > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > > > --- > > > net/sched/act_police.c | 1 - > > > 1 files changed, 0 insertions(+), 1 deletions(-) > > > > > > diff --git a/net/sched/act_police.c b/net/sched/act_police.c > > > index d6bcd64..b3b9b32 100644 > > > --- a/net/sched/act_police.c > > > +++ b/net/sched/act_police.c > > > @@ -396,7 +396,6 @@ static void __exit > > > police_cleanup_module(void) > > > { > > > tcf_unregister_action(&act_police_ops); > > > - rcu_barrier(); /* Wait for completion of call_rcu()'s (tcf_police_free_rcu) */ > > > } > > > > Very nice side-effect of having common callback code. Seems worth doing > > a review of other callers of rcu_barrier as well, to see if they still > > need to do so. > > Agreed, and good point on the review. /me wonders how this review could > be automated... Build everything as a module, and for each module check whether it uses the symbol rcu_barrier but not the symbol call_rcu. Same for the corresponding call_rcu_sched and call_rcu_bh. Also, Coccinelle could likely handle simple cases of call_rcu(function_that_calls_container_of_then_kfree), at least when the call and the function appear in the same source file. - Josh Triplett
On Mon, May 02, 2011 at 10:50:11AM -0700, Josh Triplett wrote: > On Mon, May 02, 2011 at 01:36:18AM -0700, Paul E. McKenney wrote: > > On Sun, May 01, 2011 at 08:59:35AM -0700, Josh Triplett wrote: > > > On Sun, May 01, 2011 at 06:21:25AM -0700, Paul E. McKenney wrote: > > > > From: Lai Jiangshan <laijs@cn.fujitsu.com> > > > > > > > > There is no callback of this module maybe queued > > > > since we use kfree_rcu(), we can safely remove the rcu_barrier(). > > > > > > > > Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> > > > > Acked-by: David S. Miller <davem@davemloft.net> > > > > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > > > > --- > > > > net/sched/act_police.c | 1 - > > > > 1 files changed, 0 insertions(+), 1 deletions(-) > > > > > > > > diff --git a/net/sched/act_police.c b/net/sched/act_police.c > > > > index d6bcd64..b3b9b32 100644 > > > > --- a/net/sched/act_police.c > > > > +++ b/net/sched/act_police.c > > > > @@ -396,7 +396,6 @@ static void __exit > > > > police_cleanup_module(void) > > > > { > > > > tcf_unregister_action(&act_police_ops); > > > > - rcu_barrier(); /* Wait for completion of call_rcu()'s (tcf_police_free_rcu) */ > > > > } > > > > > > Very nice side-effect of having common callback code. Seems worth doing > > > a review of other callers of rcu_barrier as well, to see if they still > > > need to do so. > > > > Agreed, and good point on the review. /me wonders how this review could > > be automated... > > Build everything as a module, and for each module check whether it uses > the symbol rcu_barrier but not the symbol call_rcu. Same for the > corresponding call_rcu_sched and call_rcu_bh. Good point -- I will give this a shot when I find AC power. > Also, Coccinelle could likely handle simple cases of > call_rcu(function_that_calls_container_of_then_kfree), at least when > the call and the function appear in the same source file. Good point -- it wasn't too hard by hand this time, but it would be a good addition to RCU checking. Thanx, Paul
diff --git a/net/sched/act_police.c b/net/sched/act_police.c index d6bcd64..b3b9b32 100644 --- a/net/sched/act_police.c +++ b/net/sched/act_police.c @@ -396,7 +396,6 @@ static void __exit police_cleanup_module(void) { tcf_unregister_action(&act_police_ops); - rcu_barrier(); /* Wait for completion of call_rcu()'s (tcf_police_free_rcu) */ } module_init(police_init_module);