rcu: Don't check irq nesting from rcu idle entry/exit
Because tasks do not nest, rcu_idle_enter() and rcu_idle_exit() do not need to check for nesting. This commit therefore moves nesting checks from rcu_idle_enter_common() to rcu_irq_exit() and from rcu_idle_exit_common() to rcu_irq_enter(). Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Josh Triplett <josh@joshtriplett.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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7cb9249900
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b6fc602014
@ -350,10 +350,6 @@ static int rcu_implicit_offline_qs(struct rcu_data *rdp)
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*/
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*/
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static void rcu_idle_enter_common(struct rcu_dynticks *rdtp, long long oldval)
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static void rcu_idle_enter_common(struct rcu_dynticks *rdtp, long long oldval)
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{
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{
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if (rdtp->dynticks_nesting) {
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trace_rcu_dyntick("--=", oldval, rdtp->dynticks_nesting);
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return;
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}
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trace_rcu_dyntick("Start", oldval, rdtp->dynticks_nesting);
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trace_rcu_dyntick("Start", oldval, rdtp->dynticks_nesting);
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if (!is_idle_task(current)) {
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if (!is_idle_task(current)) {
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struct task_struct *idle = idle_task(smp_processor_id());
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struct task_struct *idle = idle_task(smp_processor_id());
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@ -426,7 +422,10 @@ void rcu_irq_exit(void)
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oldval = rdtp->dynticks_nesting;
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oldval = rdtp->dynticks_nesting;
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rdtp->dynticks_nesting--;
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rdtp->dynticks_nesting--;
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WARN_ON_ONCE(rdtp->dynticks_nesting < 0);
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WARN_ON_ONCE(rdtp->dynticks_nesting < 0);
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rcu_idle_enter_common(rdtp, oldval);
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if (rdtp->dynticks_nesting)
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trace_rcu_dyntick("--=", oldval, rdtp->dynticks_nesting);
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else
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rcu_idle_enter_common(rdtp, oldval);
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local_irq_restore(flags);
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local_irq_restore(flags);
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}
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}
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@ -439,10 +438,6 @@ void rcu_irq_exit(void)
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*/
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*/
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static void rcu_idle_exit_common(struct rcu_dynticks *rdtp, long long oldval)
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static void rcu_idle_exit_common(struct rcu_dynticks *rdtp, long long oldval)
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{
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{
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if (oldval) {
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trace_rcu_dyntick("++=", oldval, rdtp->dynticks_nesting);
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return;
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}
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smp_mb__before_atomic_inc(); /* Force ordering w/previous sojourn. */
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smp_mb__before_atomic_inc(); /* Force ordering w/previous sojourn. */
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atomic_inc(&rdtp->dynticks);
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atomic_inc(&rdtp->dynticks);
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/* CPUs seeing atomic_inc() must see later RCU read-side crit sects */
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/* CPUs seeing atomic_inc() must see later RCU read-side crit sects */
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@ -518,7 +513,10 @@ void rcu_irq_enter(void)
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oldval = rdtp->dynticks_nesting;
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oldval = rdtp->dynticks_nesting;
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rdtp->dynticks_nesting++;
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rdtp->dynticks_nesting++;
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WARN_ON_ONCE(rdtp->dynticks_nesting == 0);
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WARN_ON_ONCE(rdtp->dynticks_nesting == 0);
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rcu_idle_exit_common(rdtp, oldval);
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if (oldval)
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trace_rcu_dyntick("++=", oldval, rdtp->dynticks_nesting);
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else
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rcu_idle_exit_common(rdtp, oldval);
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local_irq_restore(flags);
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local_irq_restore(flags);
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}
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}
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