diff options
| author | Joel Fernandes <joel@joelfernandes.org> | 2019-09-22 10:49:57 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2020-01-24 10:24:31 -0800 |
| commit | 569d767087ef56a59bc2d1d5f25ee447eeae442a (patch) | |
| tree | 5f41f31f10b0196f177e7c8f0aeadf4042f2553a /kernel/rcu | |
| parent | e6e78b004fa7e0ab455d46d27f218bf6ce178a18 (diff) | |
| download | linux-569d767087ef56a59bc2d1d5f25ee447eeae442a.tar.bz2 | |
rcu: Make kfree_rcu() use a non-atomic ->monitor_todo
Because the ->monitor_todo field is always protected by krcp->lock,
this commit downgrades from xchg() to non-atomic unmarked assignment
statements.
Signed-off-by: Joel Fernandes <joel@joelfernandes.org>
[ paulmck: Update to include early-boot kick code. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tree.c | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 0af016fdbf19..6106b9e0b5fb 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2708,7 +2708,7 @@ struct kfree_rcu_cpu { struct rcu_head *head_free; spinlock_t lock; struct delayed_work monitor_work; - int monitor_todo; + bool monitor_todo; bool initialized; }; @@ -2765,6 +2765,7 @@ static inline void kfree_rcu_drain_unlock(struct kfree_rcu_cpu *krcp, unsigned long flags) { // Attempt to start a new batch. + krcp->monitor_todo = false; if (queue_kfree_rcu_work(krcp)) { // Success! Our job is done here. spin_unlock_irqrestore(&krcp->lock, flags); @@ -2772,8 +2773,8 @@ static inline void kfree_rcu_drain_unlock(struct kfree_rcu_cpu *krcp, } // Previous RCU batch still in progress, try again later. - if (!xchg(&krcp->monitor_todo, true)) - schedule_delayed_work(&krcp->monitor_work, KFREE_DRAIN_JIFFIES); + krcp->monitor_todo = true; + schedule_delayed_work(&krcp->monitor_work, KFREE_DRAIN_JIFFIES); spin_unlock_irqrestore(&krcp->lock, flags); } @@ -2788,7 +2789,7 @@ static void kfree_rcu_monitor(struct work_struct *work) monitor_work.work); spin_lock_irqsave(&krcp->lock, flags); - if (xchg(&krcp->monitor_todo, false)) + if (krcp->monitor_todo) kfree_rcu_drain_unlock(krcp, flags); else spin_unlock_irqrestore(&krcp->lock, flags); @@ -2837,8 +2838,10 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func) // Set timer to drain after KFREE_DRAIN_JIFFIES. if (rcu_scheduler_active == RCU_SCHEDULER_RUNNING && - !xchg(&krcp->monitor_todo, true)) + !krcp->monitor_todo) { + krcp->monitor_todo = true; schedule_delayed_work(&krcp->monitor_work, KFREE_DRAIN_JIFFIES); + } if (krcp->initialized) spin_unlock(&krcp->lock); @@ -2855,10 +2858,11 @@ void __init kfree_rcu_scheduler_running(void) struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu); spin_lock_irqsave(&krcp->lock, flags); - if (!krcp->head || xchg(&krcp->monitor_todo, true)) { + if (!krcp->head || krcp->monitor_todo) { spin_unlock_irqrestore(&krcp->lock, flags); continue; } + krcp->monitor_todo = true; schedule_delayed_work(&krcp->monitor_work, KFREE_DRAIN_JIFFIES); spin_unlock_irqrestore(&krcp->lock, flags); } |