On Tue, Jul 16, 2019 at 11:53:03AM -0700, Paul E. McKenney wrote: [snip] > > > A few more things below. > > > > --- > > > > include/linux/rculist.h | 28 ++++++++++++++++++++----- > > > > include/linux/rcupdate.h | 7 +++++++ > > > > kernel/rcu/Kconfig.debug | 11 ++++++++++ > > > > kernel/rcu/update.c | 44 ++++++++++++++++++++++++---------------- > > > > 4 files changed, 67 insertions(+), 23 deletions(-) > > > > > > > > diff --git a/include/linux/rculist.h b/include/linux/rculist.h > > > > index e91ec9ddcd30..1048160625bb 100644 > > > > --- a/include/linux/rculist.h > > > > +++ b/include/linux/rculist.h > > > > @@ -40,6 +40,20 @@ static inline void INIT_LIST_HEAD_RCU(struct list_head *list) > > > > */ > > > > #define list_next_rcu(list) (*((struct list_head __rcu **)(&(list)->next))) > > > > > > > > +/* > > > > + * Check during list traversal that we are within an RCU reader > > > > + */ > > > > + > > > > +#ifdef CONFIG_PROVE_RCU_LIST > > > > > > This new Kconfig option is OK temporarily, but unless there is reason to > > > fear malfunction that a few weeks of rcutorture, 0day, and -next won't > > > find, it would be better to just use CONFIG_PROVE_RCU. The overall goal > > > is to reduce the number of RCU knobs rather than grow them, must though > > > history might lead one to believe otherwise. :-/ > > > > If you want, we can try to drop this option and just use PROVE_RCU however I > > must say there may be several warnings that need to be fixed in a short > > period of time (even a few weeks may be too short) considering the 1000+ > > uses of RCU lists. > Do many people other than me build with CONFIG_PROVE_RCU? If so, then > that would be a good reason for a temporary CONFIG_PROVE_RCU_LIST, > as in going away in a release or two once the warnings get fixed. PROVE_RCU is enabled by default with PROVE_LOCKING, so it is used quite heavilty. > > But I don't mind dropping it and it may just accelerate the fixing up of all > > callers. > > I will let you decide based on the above question. But if you have > CONFIG_PROVE_RCU_LIST, as noted below, it needs to depend on RCU_EXPERT. Ok, will make it depend. But yes for temporary purpose, I will leave it as a config and remove it later. thanks, - Joel
