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rcu: Use rcu_gp_kthread_wake() to wake up grace period kthreads

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Commit abedf8e241 ("rcu: Use simple wait queues where possible in
rcutree") converts Tree RCU's wait queues to simple wait queues,
but it incorrectly reverts the commit 2aa792e6fa ("rcu: Use
rcu_gp_kthread_wake() to wake up grace period kthreads").  This can
result in redundant self-wakeups.

This commit therefore replaces the simple wait-queue wakeups with
rcu_gp_kthread_wake(), thus avoiding the redundant wakeups.

Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Jisheng Zhang 2016-06-22 17:19:27 +08:00 committed by Paul E. McKenney
parent bedc196915
commit 94d4477673
1 changed files with 2 additions and 2 deletions
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4
kernel/rcu/tree.c
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@ -2344,7 +2344,7 @@ static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags)
WARN_ON_ONCE(!rcu_gp_in_progress(rsp)); WARN_ON_ONCE(!rcu_gp_in_progress(rsp));
WRITE_ONCE(rsp->gp_flags, READ_ONCE(rsp->gp_flags) | RCU_GP_FLAG_FQS); WRITE_ONCE(rsp->gp_flags, READ_ONCE(rsp->gp_flags) | RCU_GP_FLAG_FQS);
raw_spin_unlock_irqrestore_rcu_node(rcu_get_root(rsp), flags); raw_spin_unlock_irqrestore_rcu_node(rcu_get_root(rsp), flags);
swake_up(&rsp->gp_wq); /* Memory barrier implied by swake_up() path. */ rcu_gp_kthread_wake(rsp);
} }
/* /*
@ -2970,7 +2970,7 @@ static void force_quiescent_state(struct rcu_state *rsp)
} }
WRITE_ONCE(rsp->gp_flags, READ_ONCE(rsp->gp_flags) | RCU_GP_FLAG_FQS); WRITE_ONCE(rsp->gp_flags, READ_ONCE(rsp->gp_flags) | RCU_GP_FLAG_FQS);
raw_spin_unlock_irqrestore_rcu_node(rnp_old, flags); raw_spin_unlock_irqrestore_rcu_node(rnp_old, flags);
swake_up(&rsp->gp_wq); /* Memory barrier implied by swake_up() path. */ rcu_gp_kthread_wake(rsp);
} }
/* /*