On Mon, Jan 16, 2017 at 12:08:43AM -0800, Josh Triplett wrote: > On Sat, Jan 14, 2017 at 01:13:12AM -0800, Paul E. McKenney wrote: > > There is some confusion as to which of cond_resched() or > > cond_resched_rcu_qs() should be added to long in-kernel loops. > > This commit therefore eliminates the decision by adding RCU > > quiescent states to cond_resched(). > > > > Warning: This is a prototype. For example, it does not correctly > > handle Tasks RCU. Which is OK for the moment, given that no one > > actually uses Tasks RCU yet. > > > > Reported-by: Michal Hocko <mho...@kernel.org> > > Not-yet-signed-off-by: Paul E. McKenney <paul...@linux.vnet.ibm.com> > > Cc: Peter Zijlstra <pet...@infradead.org> > > Do you intend to merge this patch, or have you just posted it for > review? > > You may want to remove it from this 20-patch series and post it as a > separate RFC PATCH, to ensure that it doesn't get merged while still a > prototype.
It does look like I should delay this one until I get my story straight. Good catch! Thanx, Paul > > include/linux/sched.h | 3 ++- > > kernel/sched/core.c | 1 + > > 2 files changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/include/linux/sched.h b/include/linux/sched.h > > index 4d1905245c7a..1531c48f56e2 100644 > > --- a/include/linux/sched.h > > +++ b/include/linux/sched.h > > @@ -3352,10 +3352,11 @@ static inline int signal_pending_state(long state, > > struct task_struct *p) > > * cond_resched_lock() will drop the spinlock before scheduling, > > * cond_resched_softirq() will enable bhs before scheduling. > > */ > > +void rcu_all_qs(void); > > #ifndef CONFIG_PREEMPT > > extern int _cond_resched(void); > > #else > > -static inline int _cond_resched(void) { return 0; } > > +static inline int _cond_resched(void) { rcu_all_qs(); return 0; } > > #endif > > > > #define cond_resched() ({ \ > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > > index c56fb57f2991..b442f8918eb9 100644 > > --- a/kernel/sched/core.c > > +++ b/kernel/sched/core.c > > @@ -4907,6 +4907,7 @@ int __sched _cond_resched(void) > > preempt_schedule_common(); > > return 1; > > } > > + rcu_all_qs(); > > return 0; > > } > > EXPORT_SYMBOL(_cond_resched); > > -- > > 2.5.2 > > >