diff options
| author | Paul E. McKenney <paul.mckenney@linaro.org> | 2011-08-04 07:55:34 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2011-09-28 21:38:39 -0700 |
| commit | 82e78d80fc392ac7e98326bc8beeb8a679913ffd (patch) | |
| tree | 4999d3c03ed711056474c3a31512e7d3cf253b87 | |
| parent | 5c51dd7349d4bb26f845f17f85daa168f5fa03f2 (diff) | |
rcu: Simplify unboosting checks
Commit 7765be (Fix RCU_BOOST race handling current->rcu_read_unlock_special)
introduced a new ->rcu_boosted field in the task structure. This is
redundant because the existing ->rcu_boost_mutex will be non-NULL at
any time that ->rcu_boosted is nonzero. Therefore, this commit removes
->rcu_boosted and tests ->rcu_boost_mutex instead.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
| -rw-r--r-- | include/linux/sched.h | 3 | ||||
| -rw-r--r-- | kernel/rcutree_plugin.h | 20 |
2 files changed, 10 insertions, 13 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index 6ee91e20353..acca4356080 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1259,9 +1259,6 @@ struct task_struct { #ifdef CONFIG_PREEMPT_RCU int rcu_read_lock_nesting; char rcu_read_unlock_special; -#if defined(CONFIG_RCU_BOOST) && defined(CONFIG_TREE_PREEMPT_RCU) - int rcu_boosted; -#endif /* #if defined(CONFIG_RCU_BOOST) && defined(CONFIG_TREE_PREEMPT_RCU) */ struct list_head rcu_node_entry; #endif /* #ifdef CONFIG_PREEMPT_RCU */ #ifdef CONFIG_TREE_PREEMPT_RCU diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index ed70f6bf4c3..eeb38ee8ebb 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -306,6 +306,9 @@ static noinline void rcu_read_unlock_special(struct task_struct *t) int empty_exp; unsigned long flags; struct list_head *np; +#ifdef CONFIG_RCU_BOOST + struct rt_mutex *rbmp = NULL; +#endif /* #ifdef CONFIG_RCU_BOOST */ struct rcu_node *rnp; int special; @@ -351,6 +354,7 @@ static noinline void rcu_read_unlock_special(struct task_struct *t) smp_mb(); /* ensure expedited fastpath sees end of RCU c-s. */ np = rcu_next_node_entry(t, rnp); list_del_init(&t->rcu_node_entry); + t->rcu_blocked_node = NULL; trace_rcu_unlock_preempted_task("rcu_preempt", rnp->gpnum, t->pid); if (&t->rcu_node_entry == rnp->gp_tasks) @@ -360,13 +364,12 @@ static noinline void rcu_read_unlock_special(struct task_struct *t) #ifdef CONFIG_RCU_BOOST if (&t->rcu_node_entry == rnp->boost_tasks) rnp->boost_tasks = np; - /* Snapshot and clear ->rcu_boosted with rcu_node lock held. */ - if (t->rcu_boosted) { - special |= RCU_READ_UNLOCK_BOOSTED; - t->rcu_boosted = 0; + /* Snapshot/clear ->rcu_boost_mutex with rcu_node lock held. */ + if (t->rcu_boost_mutex) { + rbmp = t->rcu_boost_mutex; + t->rcu_boost_mutex = NULL; } #endif /* #ifdef CONFIG_RCU_BOOST */ - t->rcu_blocked_node = NULL; /* * If this was the last task on the current list, and if @@ -387,10 +390,8 @@ static noinline void rcu_read_unlock_special(struct task_struct *t) #ifdef CONFIG_RCU_BOOST /* Unboost if we were boosted. */ - if (special & RCU_READ_UNLOCK_BOOSTED) { - rt_mutex_unlock(t->rcu_boost_mutex); - t->rcu_boost_mutex = NULL; - } + if (rbmp) + rt_mutex_unlock(rbmp); #endif /* #ifdef CONFIG_RCU_BOOST */ /* @@ -1206,7 +1207,6 @@ static int rcu_boost(struct rcu_node *rnp) t = container_of(tb, struct task_struct, rcu_node_entry); rt_mutex_init_proxy_locked(&mtx, t); t->rcu_boost_mutex = &mtx; - t->rcu_boosted = 1; raw_spin_unlock_irqrestore(&rnp->lock, flags); rt_mutex_lock(&mtx); /* Side effect: boosts task t's priority. */ rt_mutex_unlock(&mtx); /* Keep lockdep happy. */ |