From 8e9aa8f067d2dcd9457980ced618e1cffbcfba46 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 12 Nov 2009 22:35:04 -0800 Subject: [PATCH] rcu: Simplify association of forced quiescent states with grace periods The force_quiescent_state() function also took a snapshot of the ->completed field, which was as obnoxious as it was in rcu_sched_qs() and friends. So snapshot ->gpnum-1. Also, since the dyntick_record_completed() and dyntick_recall_completed() functions are now simple assignments that are independent of CONFIG_NO_HZ, and since their names are now misleading, get rid of them. Signed-off-by: Paul E. McKenney Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <12580941042308-git-send-email-> Signed-off-by: Ingo Molnar --- kernel/rcutree.c | 27 +++------------------------ 1 file changed, 3 insertions(+), 24 deletions(-) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index b4efb9e..3df0438 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -178,29 +178,9 @@ static struct rcu_node *rcu_get_root(struct rcu_state *rsp) return &rsp->node[0]; } -/* - * Record the specified "completed" value, which is later used to validate - * dynticks counter manipulations and CPU-offline checks. Specify - * "rsp->completed - 1" to unconditionally invalidate any future dynticks - * manipulations and CPU-offline checks. Such invalidation is useful at - * the beginning of a grace period. - */ -static void dyntick_record_completed(struct rcu_state *rsp, long comp) -{ - rsp->completed_fqs = comp; -} - #ifdef CONFIG_SMP /* - * Recall the previously recorded value of the completion for dynticks. - */ -static long dyntick_recall_completed(struct rcu_state *rsp) -{ - return rsp->completed_fqs; -} - -/* * If the specified CPU is offline, tell the caller that it is in * a quiescent state. Otherwise, whack it with a reschedule IPI. * Grace periods can end up waiting on an offline CPU when that @@ -702,7 +682,6 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags) rsp->signaled = RCU_GP_INIT; /* Hold off force_quiescent_state. */ rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS; record_gp_stall_check_time(rsp); - dyntick_record_completed(rsp, rsp->completed - 1); /* Special-case the common single-level case. */ if (NUM_RCU_NODES == 1) { @@ -1214,7 +1193,7 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed) goto unlock_ret; /* no emergency and done recently. */ rsp->n_force_qs++; spin_lock(&rnp->lock); - lastcomp = rsp->completed; + lastcomp = rsp->gpnum - 1; signaled = rsp->signaled; rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS; if (lastcomp == rsp->gpnum) { @@ -1248,7 +1227,7 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed) if (lastcomp == rsp->completed && rsp->signaled == signaled) { rsp->signaled = RCU_FORCE_QS; - dyntick_record_completed(rsp, lastcomp); + rsp->completed_fqs = lastcomp; forcenow = signaled == RCU_SAVE_COMPLETED; } spin_unlock(&rnp->lock); @@ -1259,7 +1238,7 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed) case RCU_FORCE_QS: /* Check dyntick-idle state, send IPI to laggarts. */ - if (rcu_process_dyntick(rsp, dyntick_recall_completed(rsp), + if (rcu_process_dyntick(rsp, rsp->completed_fqs, rcu_implicit_dynticks_qs)) goto unlock_ret; -- 2.7.4