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Date: Thu, 2 Jul 2015 12:35:45 -0700 From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com> To: Peter Zijlstra <peterz@...radead.org> Cc: linux-kernel@...r.kernel.org, mingo@...nel.org, laijs@...fujitsu.com, dipankar@...ibm.com, akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com, josh@...htriplett.org, tglx@...utronix.de, rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com, dvhart@...ux.intel.com, fweisbec@...il.com, oleg@...hat.com, bobby.prani@...il.com Subject: Re: [PATCH RFC tip/core/rcu 2/5] rcu: Short-circuit normal GPs via expedited GPs On Thu, Jul 02, 2015 at 06:48:16PM +0200, Peter Zijlstra wrote: > On Thu, Jul 02, 2015 at 07:06:17AM -0700, Paul E. McKenney wrote: > > Or is your point that RCU_GP_DONE_FQS is a bad name? Perhaps I should > > change it to something like RCU_GP_DOING_FQS. Or am I still missing > > something here? > > Yes, that might have been the root of my confusion. OK, how about this, then? Thanx, Paul ------------------------------------------------------------------------ rcu: Rename RCU_GP_DONE_FQS to RCU_GP_DOING_FQS The grace-period kthread sleeps waiting to do a force-quiescent-state scan, and when awakened sets rsp->gp_state to RCU_GP_DONE_FQS. However, this is confusing because the kthread has not done the force-quiescent-state, but is instead just starting to do it. This commit therefore renames RCU_GP_DONE_FQS to RCU_GP_DOING_FQS in order to make things a bit easier on reviewers. Reported-by: Peter Zijlstra <peterz@...radead.org> Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 2afb8e8c5134..e1d9909fd59d 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2088,7 +2088,7 @@ static int __noreturn rcu_gp_kthread(void *arg) rsp->gp_state = RCU_GP_WAIT_FQS; ret = wait_event_interruptible_timeout(rsp->gp_wq, rcu_gp_fqs_check_wake(rsp, &gf), j); - rsp->gp_state = RCU_GP_DONE_FQS; + rsp->gp_state = RCU_GP_DOING_FQS; /* Locking provides needed memory barriers. */ /* If grace period done, leave loop. */ if (!READ_ONCE(rnp->qsmask) && diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index cb402b5c2e71..852b810df38e 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -533,7 +533,7 @@ struct rcu_state { #define RCU_GP_WAIT_GPS 1 /* Wait for grace-period start. */ #define RCU_GP_DONE_GPS 2 /* Wait done for grace-period start. */ #define RCU_GP_WAIT_FQS 3 /* Wait for force-quiescent-state time. */ -#define RCU_GP_DONE_FQS 4 /* Wait done for force-quiescent-state time. */ +#define RCU_GP_DOING_FQS 4 /* Wait done for force-quiescent-state time. */ #define RCU_GP_CLEANUP 5 /* Grace-period cleanup started. */ #define RCU_GP_CLEANED 6 /* Grace-period cleanup complete. */ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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