Commit-ID: c0da313e090d6e7130d0c3005245176296c24e4a
Gitweb: https://git.kernel.org/tip/c0da313e090d6e7130d0c3005245176296c24e4a
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Fri, 22 Sep 2017 09:58:47 -0700
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Thu, 19 Oct 2017 12:13:36 -0700
rcu: Add extended-quiescent-state testing advice
If you add or remove calls to rcu_idle_enter(), rcu_user_enter(),
rcu_irq_exit(), rcu_irq_exit_irqson(), rcu_idle_exit(), rcu_user_exit(),
rcu_irq_enter(), rcu_irq_enter_irqson(), rcu_nmi_enter(), or
rcu_nmi_exit(), you should run a full set of tests on a kernel built
with CONFIG_RCU_EQS_DEBUG=y.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
kernel/rcu/tree.c | 30 ++++++++++++++++++++++++++++++
1 file changed, 30 insertions(+)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index b0ad62b..d234356 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -837,6 +837,9 @@ static void rcu_eqs_enter(bool user)
* We crowbar the ->dynticks_nesting field to zero to allow for
* the possibility of usermode upcalls having messed up our count
* of interrupt nesting level during the prior busy period.
+ *
+ * If you add or remove a call to rcu_idle_enter(), be sure to test with
+ * CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_idle_enter(void)
{
@@ -852,6 +855,9 @@ void rcu_idle_enter(void)
* is permitted between this call and rcu_user_exit(). This way the
* CPU doesn't need to maintain the tick for RCU maintenance purposes
* when the CPU runs in userspace.
+ *
+ * If you add or remove a call to rcu_user_enter(), be sure to test with
+ * CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_user_enter(void)
{
@@ -875,6 +881,9 @@ void rcu_user_enter(void)
* Use things like work queues to work around this limitation.
*
* You have been warned.
+ *
+ * If you add or remove a call to rcu_irq_exit(), be sure to test with
+ * CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_irq_exit(void)
{
@@ -899,6 +908,9 @@ void rcu_irq_exit(void)
/*
* Wrapper for rcu_irq_exit() where interrupts are enabled.
+ *
+ * If you add or remove a call to rcu_irq_exit_irqson(), be sure to test
+ * with CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_irq_exit_irqson(void)
{
@@ -971,6 +983,9 @@ static void rcu_eqs_exit(bool user)
* allow for the possibility of usermode upcalls messing up our count
* of interrupt nesting level during the busy period that is just
* now starting.
+ *
+ * If you add or remove a call to rcu_idle_exit(), be sure to test with
+ * CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_idle_exit(void)
{
@@ -987,6 +1002,9 @@ void rcu_idle_exit(void)
*
* Exit RCU idle mode while entering the kernel because it can
* run a RCU read side critical section anytime.
+ *
+ * If you add or remove a call to rcu_user_exit(), be sure to test with
+ * CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_user_exit(void)
{
@@ -1012,6 +1030,9 @@ void rcu_user_exit(void)
* Use things like work queues to work around this limitation.
*
* You have been warned.
+ *
+ * If you add or remove a call to rcu_irq_enter(), be sure to test with
+ * CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_irq_enter(void)
{
@@ -1037,6 +1058,9 @@ void rcu_irq_enter(void)
/*
* Wrapper for rcu_irq_enter() where interrupts are enabled.
+ *
+ * If you add or remove a call to rcu_irq_enter_irqson(), be sure to test
+ * with CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_irq_enter_irqson(void)
{
@@ -1055,6 +1079,9 @@ void rcu_irq_enter_irqson(void)
* 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)
{
@@ -1087,6 +1114,9 @@ void rcu_nmi_enter(void)
* 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)
{
--
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