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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2017-03-21 15:28:14 +0100
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2017-04-18 20:38:21 +0200
commit031aeee000e895247eafa4233c2d193dd39d4ea2 (patch)
tree8a8f567d15a94788150ec924c726ddc324c55ead /kernel/rcu/tree_exp.h
parentsrcu: Fix bogus try_check_zero() comment (diff)
downloadlinux-031aeee000e895247eafa4233c2d193dd39d4ea2.tar.xz
linux-031aeee000e895247eafa4233c2d193dd39d4ea2.zip
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 <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcu/tree_exp.h')
-rw-r--r--kernel/rcu/tree_exp.h9
1 files changed, 4 insertions, 5 deletions
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. */