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 <[email protected]> Not-yet-signed-off-by: Paul E. McKenney <[email protected]> Cc: Peter Zijlstra <[email protected]> --- 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
