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| author | Lai Jiangshan <laijs@linux.alibaba.com> | 2019-11-01 12:06:22 +0100 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2020-01-24 19:27:33 +0100 |
| commit | 2eeba5838fd8c5e19bb91e25624116936348e7af (patch) | |
| tree | 2b353e5078dbf4b377b776924771983cb70fbb77 /kernel/rcu | |
| parent | rcu: Rename some instance of CONFIG_PREEMPTION to CONFIG_PREEMPT_RCU (diff) | |
| download | linux-2eeba5838fd8c5e19bb91e25624116936348e7af.tar.xz linux-2eeba5838fd8c5e19bb91e25624116936348e7af.zip | |
rcu: Clear .exp_hint only when deferred quiescent state has been reported
Currently, the .exp_hint flag is cleared in rcu_read_unlock_special(),
which works, but which can also prevent subsequent rcu_read_unlock() calls
from helping expedite the quiescent state needed by an ongoing expedited
RCU grace period. This commit therefore defers clearing of .exp_hint
from rcu_read_unlock_special() to rcu_preempt_deferred_qs_irqrestore(),
thus ensuring that intervening calls to rcu_read_unlock() have a chance
to help end the expedited grace period.
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tree_plugin.h | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 8cdce111ea73..7487c7930a47 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -444,6 +444,7 @@ rcu_preempt_deferred_qs_irqrestore(struct task_struct *t, unsigned long flags) local_irq_restore(flags); return; } + t->rcu_read_unlock_special.b.exp_hint = false; t->rcu_read_unlock_special.b.deferred_qs = false; if (special.b.need_qs) { rcu_qs(); @@ -610,7 +611,6 @@ static void rcu_read_unlock_special(struct task_struct *t) struct rcu_data *rdp = this_cpu_ptr(&rcu_data); struct rcu_node *rnp = rdp->mynode; - t->rcu_read_unlock_special.b.exp_hint = false; exp = (t->rcu_blocked_node && t->rcu_blocked_node->exp_tasks) || (rdp->grpmask & rnp->expmask) || tick_nohz_full_cpu(rdp->cpu); @@ -640,7 +640,6 @@ static void rcu_read_unlock_special(struct task_struct *t) local_irq_restore(flags); return; } - WRITE_ONCE(t->rcu_read_unlock_special.b.exp_hint, false); rcu_preempt_deferred_qs_irqrestore(t, flags); } |