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rcu: Improve grace-period start logic
This commit improves grace-period start logic by checking ->gp_flags under the lock and by issuing a warning if a grace period is already in progress. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
parent
272b98c645
commit
f7be820939
1 changed files with 12 additions and 5 deletions
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@ -1297,7 +1297,7 @@ static void note_gp_changes(struct rcu_state *rsp, struct rcu_data *rdp)
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}
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/*
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* Initialize a new grace period.
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* Initialize a new grace period. Return 0 if no grace period required.
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*/
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static int rcu_gp_init(struct rcu_state *rsp)
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{
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@ -1306,10 +1306,18 @@ static int rcu_gp_init(struct rcu_state *rsp)
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rcu_bind_gp_kthread();
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raw_spin_lock_irq(&rnp->lock);
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if (rsp->gp_flags == 0) {
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/* Spurious wakeup, tell caller to go back to sleep. */
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raw_spin_unlock_irq(&rnp->lock);
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return 0;
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}
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rsp->gp_flags = 0; /* Clear all flags: New grace period. */
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if (rcu_gp_in_progress(rsp)) {
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/* Grace period already in progress, don't start another. */
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if (WARN_ON_ONCE(rcu_gp_in_progress(rsp))) {
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/*
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* Grace period already in progress, don't start another.
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* Not supposed to be able to happen.
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*/
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raw_spin_unlock_irq(&rnp->lock);
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return 0;
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}
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@ -1474,8 +1482,7 @@ static int __noreturn rcu_gp_kthread(void *arg)
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wait_event_interruptible(rsp->gp_wq,
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rsp->gp_flags &
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RCU_GP_FLAG_INIT);
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if ((rsp->gp_flags & RCU_GP_FLAG_INIT) &&
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rcu_gp_init(rsp))
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if (rcu_gp_init(rsp))
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break;
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cond_resched();
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flush_signals(current);
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