"mask_ofl_ipi" is used for iterate CPUs which IPIs are needed to send
to, however in the IPI sending loop, "mask_ofl_ipi" along with another
variable "mask_ofl_test" might also get modified to record which CPU's
quiesent state can be reported by sync_rcu_exp_select_node_cpus(). Two
variables seems to be redundant for such a propose, so this patch clean
things a little by solely using "mask_ofl_test" for recording and
"mask_ofl_ipi" for iteration. This would improve the readibility of the
IPI sending loop in sync_rcu_exp_select_node_cpus().
Signed-off-by: Boqun Feng <boqun.feng@xxxxxxxxx>
---
kernel/rcu/tree_exp.h | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
index 69c5aa64fcfd..212470018752 100644
--- a/kernel/rcu/tree_exp.h
+++ b/kernel/rcu/tree_exp.h
@@ -387,10 +387,10 @@ static void sync_rcu_exp_select_node_cpus(struct work_struct *wp)
}
ret = smp_call_function_single(cpu, rcu_exp_handler, NULL, 0);
put_cpu();
- if (!ret) {
- mask_ofl_ipi &= ~mask;
+ /* The CPU responses the IPI, and will report QS itself */
+ if (!ret)
continue;
- }
+
/* Failed, raced with CPU hotplug operation. */
raw_spin_lock_irqsave_rcu_node(rnp, flags);
if ((rnp->qsmaskinitnext & mask) &&
@@ -401,13 +401,12 @@ static void sync_rcu_exp_select_node_cpus(struct work_struct *wp)
schedule_timeout_uninterruptible(1);
goto retry_ipi;
}
- /* CPU really is offline, so we can ignore it. */
- if (!(rnp->expmask & mask))
- mask_ofl_ipi &= ~mask;
+ /* CPU really is offline, and we need its QS to pass GP. */
+ if (rnp->expmask & mask)
+ mask_ofl_test |= mask;
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
}
/* Report quiescent states for those that went offline. */
- mask_ofl_test |= mask_ofl_ipi;
if (mask_ofl_test)
rcu_report_exp_cpu_mult(rnp, mask_ofl_test, false);
}
--
2.23.0
