Messages in this thread |  | | Date | Fri, 15 Jul 2016 15:27:09 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH 2/2] locking/percpu-rwsem: Introduce bias knob |
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On 07/14, Peter Zijlstra wrote: > > On Thu, Jul 14, 2016 at 08:43:51PM +0200, Oleg Nesterov wrote: > > > > Oh well... I personally do not think this is what we want... Can't > > we just add the stupid rcu_sync_enter() into cgroup_init() at least > > for now? Yes, this means the unnecessary .sync() at boot time, but > > it will go away after cleanups I am going to send. > > Something like so then?
OK, agreed,
> --- > --- a/include/linux/rcu_sync.h > +++ b/include/linux/rcu_sync.h > @@ -59,6 +59,7 @@ static inline bool rcu_sync_is_idle(stru > } > > extern void rcu_sync_init(struct rcu_sync *, enum rcu_sync_type); > +extern void rcu_sync_sabotage(struct rcu_sync *); > extern void rcu_sync_enter(struct rcu_sync *); > extern void rcu_sync_exit(struct rcu_sync *); > extern void rcu_sync_dtor(struct rcu_sync *); > --- a/kernel/cgroup.c > +++ b/kernel/cgroup.c > @@ -5609,6 +5609,8 @@ int __init cgroup_init(void) > BUG_ON(cgroup_init_cftypes(NULL, cgroup_dfl_base_files)); > BUG_ON(cgroup_init_cftypes(NULL, cgroup_legacy_base_files)); > > + rcu_sync_sabotage(&cgroup_threadgroup_rwsem.rss);
Heh ;) I too think it should be renamed. I'd suggest
__rcu_sync_enter(rss);
although I do not really mind and agree with any name.
Hopefully I'll send some cleanups soon, rcu_sync_enter() will be re-implemented as
rcu_sync_enter(rss) { if (__rcu_sync_enter(rss)) __rcu_sync_wait(rss); }
> + * rcu_sync_sabotage() - Sabotage a fresh rcu_sync instance > + * @rsp: Pointer to rcu_sync structure to be sabotaged > + * > + * Must be called after rcu_sync_init() and before first use.
OK. And after those cleanups __rcu_sync_enter() can be called at any time.
Oleg.
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