Messages in this thread | | | Date | Fri, 15 Jun 2012 16:52:40 -0700 | From | Josh Triplett <> | Subject | Re: [PATCH tip/core/rcu 13/15] rcu: Introduce for_each_rcu_flavor() and use it |
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On Fri, Jun 15, 2012 at 02:06:08PM -0700, Paul E. McKenney wrote: > From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> > > The arrival of TREE_PREEMPT_RCU some years back included some ugly > code involving either #ifdef or #ifdef'ed wrapper functions to iterate > over all non-SRCU flavors of RCU. This commit therefore introduces > a for_each_rcu_flavor() iterator over the rcu_state structures for each > flavor of RCU to clean up a bit of the ugliness. > > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Great cleanup!
A few comments below, though.
> kernel/rcutree.c | 53 +++++++++++++--------- > kernel/rcutree.h | 12 ++--- > kernel/rcutree_plugin.h | 116 ----------------------------------------------- > 3 files changed, 36 insertions(+), 145 deletions(-)
Awesome diffstat.
> diff --git a/kernel/rcutree.c b/kernel/rcutree.c > index bd4e41c..75ad92a 100644 > --- a/kernel/rcutree.c > +++ b/kernel/rcutree.c > @@ -84,6 +84,7 @@ struct rcu_state rcu_bh_state = RCU_STATE_INITIALIZER(rcu_bh, call_rcu_bh); > DEFINE_PER_CPU(struct rcu_data, rcu_bh_data); > > static struct rcu_state *rcu_state; > +LIST_HEAD(rcu_struct_flavors);
Does any means exist to turn this into a constant array known at compile time rather than a runtime linked list? Having this as a compile-time constant may allow the compiler to unroll for_each_rcu_flavor and potentially inline the calls inside it.
> @@ -2539,9 +2548,10 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptible) > > static void __cpuinit rcu_prepare_cpu(int cpu) > { > - rcu_init_percpu_data(cpu, &rcu_sched_state, 0); > - rcu_init_percpu_data(cpu, &rcu_bh_state, 0); > - rcu_preempt_init_percpu_data(cpu); > + struct rcu_state *rsp; > + > + for_each_rcu_flavor(rsp) > + rcu_init_percpu_data(cpu, rsp, 0);
This results in passing 0 as the "preemptible" parameter of rcu_init_percpu_data, which seems wrong if the preemptible parameter has any meaning at all. :)
> @@ -2577,18 +2588,15 @@ static int __cpuinit rcu_cpu_notify(struct notifier_block *self, > * touch any data without introducing corruption. We send the > * dying CPU's callbacks to an arbitrarily chosen online CPU. > */ > - rcu_cleanup_dying_cpu(&rcu_bh_state); > - rcu_cleanup_dying_cpu(&rcu_sched_state); > - rcu_preempt_cleanup_dying_cpu(); > - rcu_cleanup_after_idle(cpu); > + for_each_rcu_flavor(rsp) > + rcu_cleanup_dying_cpu(rsp);
Why did rcu_cleanup_after_idle go away here?
- Josh Triplett
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