From 031aeee000e895247eafa4233c2d193dd39d4ea2 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 21 Mar 2017 07:28:14 -0700 Subject: srcu: Improve rcu_seq grace-period-counter abstraction The expedited grace-period code contains several open-coded shifts know the format of an rcu_seq grace-period counter, which is not particularly good style. This commit therefore creates a new rcu_seq_ctr() function that extracts the counter portion of the counter, and an rcu_seq_state() function that extracts the low-order state bit. This commit prepares for SRCU callback parallelization, which will require two state bits. Signed-off-by: Paul E. McKenney --- kernel/rcu/tree_exp.h | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) (limited to 'kernel/rcu/tree_exp.h') diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index 027e123d93c7..e513b4ab1197 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -292,7 +292,7 @@ static bool exp_funnel_lock(struct rcu_state *rsp, unsigned long s) trace_rcu_exp_funnel_lock(rsp->name, rnp->level, rnp->grplo, rnp->grphi, TPS("wait")); - wait_event(rnp->exp_wq[(s >> 1) & 0x3], + wait_event(rnp->exp_wq[rcu_seq_ctr(s) & 0x3], sync_exp_work_done(rsp, &rdp->exp_workdone2, s)); return true; @@ -534,7 +534,7 @@ static void rcu_exp_wait_wake(struct rcu_state *rsp, unsigned long s) spin_unlock(&rnp->exp_lock); } smp_mb(); /* All above changes before wakeup. */ - wake_up_all(&rnp->exp_wq[(rsp->expedited_sequence >> 1) & 0x3]); + wake_up_all(&rnp->exp_wq[rcu_seq_ctr(rsp->expedited_sequence) & 0x3]); } trace_rcu_exp_grace_period(rsp->name, s, TPS("endwake")); mutex_unlock(&rsp->exp_wake_mutex); @@ -612,9 +612,8 @@ static void _synchronize_rcu_expedited(struct rcu_state *rsp, /* Wait for expedited grace period to complete. */ rdp = per_cpu_ptr(rsp->rda, raw_smp_processor_id()); rnp = rcu_get_root(rsp); - wait_event(rnp->exp_wq[(s >> 1) & 0x3], - sync_exp_work_done(rsp, - &rdp->exp_workdone0, s)); + wait_event(rnp->exp_wq[rcu_seq_ctr(s) & 0x3], + sync_exp_work_done(rsp, &rdp->exp_workdone0, s)); smp_mb(); /* Workqueue actions happen before return. */ /* Let the next expedited grace period start. */ -- cgit