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Message-Id: <1512157008-22355-3-git-send-email-paulmck@linux.vnet.ibm.com>
Date: Fri, 1 Dec 2017 11:36:34 -0800
From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To: linux-kernel@...r.kernel.org
Cc: mingo@...nel.org, jiangshanlai@...il.com, dipankar@...ibm.com,
akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
fweisbec@...il.com, oleg@...hat.com,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 03/17] rcu: Move rcu_nmi_{enter,exit}() to prepare for consolidation
This is a code-motion-only commit that prepares to define rcu_irq_enter()
in terms of rcu_nmi_enter() and rcu_irq_exit() in terms of rcu_irq_exit().
Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
kernel/rcu/tree.c | 150 +++++++++++++++++++++++++++---------------------------
1 file changed, 75 insertions(+), 75 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 49f661bb8ffe..419f3c38e1b6 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -867,6 +867,44 @@ void rcu_user_enter(void)
#endif /* CONFIG_NO_HZ_FULL */
/**
+ * rcu_nmi_exit - inform RCU of exit from NMI context
+ *
+ * If we are returning from the outermost NMI handler that interrupted an
+ * RCU-idle period, update rdtp->dynticks and rdtp->dynticks_nmi_nesting
+ * to let the RCU grace-period handling know that the CPU is back to
+ * being RCU-idle.
+ *
+ * If you add or remove a call to rcu_nmi_exit(), be sure to test
+ * with CONFIG_RCU_EQS_DEBUG=y.
+ */
+void rcu_nmi_exit(void)
+{
+ struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
+
+ /*
+ * Check for ->dynticks_nmi_nesting underflow and bad ->dynticks.
+ * (We are exiting an NMI handler, so RCU better be paying attention
+ * to us!)
+ */
+ WARN_ON_ONCE(rdtp->dynticks_nmi_nesting <= 0);
+ WARN_ON_ONCE(rcu_dynticks_curr_cpu_in_eqs());
+
+ /*
+ * If the nesting level is not 1, the CPU wasn't RCU-idle, so
+ * leave it in non-RCU-idle state.
+ */
+ if (rdtp->dynticks_nmi_nesting != 1) {
+ WRITE_ONCE(rdtp->dynticks_nmi_nesting, /* No store tearing. */
+ rdtp->dynticks_nmi_nesting - 2);
+ return;
+ }
+
+ /* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */
+ WRITE_ONCE(rdtp->dynticks_nmi_nesting, 0); /* Avoid store tearing. */
+ rcu_dynticks_eqs_enter();
+}
+
+/**
* rcu_irq_exit - inform RCU that current CPU is exiting irq towards idle
*
* Exit from an interrupt handler, which might possibly result in entering
@@ -1013,6 +1051,43 @@ void rcu_user_exit(void)
#endif /* CONFIG_NO_HZ_FULL */
/**
+ * rcu_nmi_enter - inform RCU of entry to NMI context
+ *
+ * If the CPU was idle from RCU's viewpoint, update rdtp->dynticks and
+ * rdtp->dynticks_nmi_nesting to let the RCU grace-period handling know
+ * that the CPU is active. This implementation permits nested NMIs, as
+ * long as the nesting level does not overflow an int. (You will probably
+ * run out of stack space first.)
+ *
+ * If you add or remove a call to rcu_nmi_enter(), be sure to test
+ * with CONFIG_RCU_EQS_DEBUG=y.
+ */
+void rcu_nmi_enter(void)
+{
+ struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
+ int incby = 2;
+
+ /* Complain about underflow. */
+ WARN_ON_ONCE(rdtp->dynticks_nmi_nesting < 0);
+
+ /*
+ * If idle from RCU viewpoint, atomically increment ->dynticks
+ * to mark non-idle and increment ->dynticks_nmi_nesting by one.
+ * Otherwise, increment ->dynticks_nmi_nesting by two. This means
+ * if ->dynticks_nmi_nesting is equal to one, we are guaranteed
+ * to be in the outermost NMI handler that interrupted an RCU-idle
+ * period (observation due to Andy Lutomirski).
+ */
+ if (rcu_dynticks_curr_cpu_in_eqs()) {
+ rcu_dynticks_eqs_exit();
+ incby = 1;
+ }
+ WRITE_ONCE(rdtp->dynticks_nmi_nesting, /* Prevent store tearing. */
+ rdtp->dynticks_nmi_nesting + incby);
+ barrier();
+}
+
+/**
* rcu_irq_enter - inform RCU that current CPU is entering irq away from idle
*
* Enter an interrupt handler, which might possibly result in exiting
@@ -1071,81 +1146,6 @@ void rcu_irq_enter_irqson(void)
}
/**
- * rcu_nmi_enter - inform RCU of entry to NMI context
- *
- * If the CPU was idle from RCU's viewpoint, update rdtp->dynticks and
- * rdtp->dynticks_nmi_nesting to let the RCU grace-period handling know
- * that the CPU is active. This implementation permits nested NMIs, as
- * long as the nesting level does not overflow an int. (You will probably
- * run out of stack space first.)
- *
- * If you add or remove a call to rcu_nmi_enter(), be sure to test
- * with CONFIG_RCU_EQS_DEBUG=y.
- */
-void rcu_nmi_enter(void)
-{
- struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
- int incby = 2;
-
- /* Complain about underflow. */
- WARN_ON_ONCE(rdtp->dynticks_nmi_nesting < 0);
-
- /*
- * If idle from RCU viewpoint, atomically increment ->dynticks
- * to mark non-idle and increment ->dynticks_nmi_nesting by one.
- * Otherwise, increment ->dynticks_nmi_nesting by two. This means
- * if ->dynticks_nmi_nesting is equal to one, we are guaranteed
- * to be in the outermost NMI handler that interrupted an RCU-idle
- * period (observation due to Andy Lutomirski).
- */
- if (rcu_dynticks_curr_cpu_in_eqs()) {
- rcu_dynticks_eqs_exit();
- incby = 1;
- }
- WRITE_ONCE(rdtp->dynticks_nmi_nesting, /* Prevent store tearing. */
- rdtp->dynticks_nmi_nesting + incby);
- barrier();
-}
-
-/**
- * rcu_nmi_exit - inform RCU of exit from NMI context
- *
- * If we are returning from the outermost NMI handler that interrupted an
- * RCU-idle period, update rdtp->dynticks and rdtp->dynticks_nmi_nesting
- * to let the RCU grace-period handling know that the CPU is back to
- * being RCU-idle.
- *
- * If you add or remove a call to rcu_nmi_exit(), be sure to test
- * with CONFIG_RCU_EQS_DEBUG=y.
- */
-void rcu_nmi_exit(void)
-{
- struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
-
- /*
- * Check for ->dynticks_nmi_nesting underflow and bad ->dynticks.
- * (We are exiting an NMI handler, so RCU better be paying attention
- * to us!)
- */
- WARN_ON_ONCE(rdtp->dynticks_nmi_nesting <= 0);
- WARN_ON_ONCE(rcu_dynticks_curr_cpu_in_eqs());
-
- /*
- * If the nesting level is not 1, the CPU wasn't RCU-idle, so
- * leave it in non-RCU-idle state.
- */
- if (rdtp->dynticks_nmi_nesting != 1) {
- WRITE_ONCE(rdtp->dynticks_nmi_nesting, /* No store tearing. */
- rdtp->dynticks_nmi_nesting - 2);
- return;
- }
-
- /* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */
- WRITE_ONCE(rdtp->dynticks_nmi_nesting, 0); /* Avoid store tearing. */
- rcu_dynticks_eqs_enter();
-}
-
-/**
* rcu_is_watching - see if RCU thinks that the current CPU is idle
*
* Return true if RCU is watching the running CPU, which means that this
--
2.5.2
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