On Mon, Feb 17, 2014 at 01:40:27PM -0800, Paul E. McKenney wrote: > From: "Paul E. McKenney" <[email protected]> > > If CONFIG_RCU_NOCB_CPU_ALL=y, then no CPU will ever have RCU callbacks > because these callbacks will instead be handled by the rcuo kthreads. > However, the current version of RCU_FAST_NO_HZ nevertheless checks for RCU > callbacks. This commit therefore creates static inline implementations > of rcu_prepare_for_idle() and rcu_cleanup_after_idle() that are no-ops > when CONFIG_RCU_NOCB_CPU_ALL=y.
"creates static inline implementations" isn't quite accurate; they're static, and in the header, and the compiler is likely to inline the no-op versions, but they're not actually marked as inline. The commit message should just say that it turns the implementations into no-ops. > Signed-off-by: Paul E. McKenney <[email protected]> Reviewed-by: Josh Triplett <[email protected]> > --- > kernel/rcu/tree_plugin.h | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h > index 820b06aefbee..41afc3fbfb6c 100644 > --- a/kernel/rcu/tree_plugin.h > +++ b/kernel/rcu/tree_plugin.h > @@ -1658,7 +1658,7 @@ extern int tick_nohz_active; > * only if it has been awhile since the last time we did so. Afterwards, > * if there are any callbacks ready for immediate invocation, return true. > */ > -static bool rcu_try_advance_all_cbs(void) > +static bool __maybe_unused rcu_try_advance_all_cbs(void) > { > bool cbs_ready = false; > struct rcu_data *rdp; > @@ -1743,6 +1743,7 @@ int rcu_needs_cpu(int cpu, unsigned long *dj) > */ > static void rcu_prepare_for_idle(int cpu) > { > +#ifndef CONFIG_RCU_NOCB_CPU_ALL > struct rcu_data *rdp; > struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu); > struct rcu_node *rnp; > @@ -1794,6 +1795,7 @@ static void rcu_prepare_for_idle(int cpu) > rcu_accelerate_cbs(rsp, rnp, rdp); > raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ > } > +#endif /* #ifndef CONFIG_RCU_NOCB_CPU_ALL */ > } > > /* > @@ -1803,11 +1805,12 @@ static void rcu_prepare_for_idle(int cpu) > */ > static void rcu_cleanup_after_idle(int cpu) > { > - > +#ifndef CONFIG_RCU_NOCB_CPU_ALL > if (rcu_is_nocb_cpu(cpu)) > return; > if (rcu_try_advance_all_cbs()) > invoke_rcu_core(); > +#endif /* #ifndef CONFIG_RCU_NOCB_CPU_ALL */ > } > > /* > -- > 1.8.1.5 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
