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rcu: Add extended-quiescent-state testing advice

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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@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2017-09-22 09:58:47 -07:00
parent 02a7c234e5
commit c0da313e09
1 changed files with 30 additions and 0 deletions
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30
kernel/rcu/tree.c
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@ -837,6 +837,9 @@ static void rcu_eqs_enter(bool user)
* We crowbar the ->dynticks_nesting field to zero to allow for * We crowbar the ->dynticks_nesting field to zero to allow for
* the possibility of usermode upcalls having messed up our count * the possibility of usermode upcalls having messed up our count
* of interrupt nesting level during the prior busy period. * 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) 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 * is permitted between this call and rcu_user_exit(). This way the
* CPU doesn't need to maintain the tick for RCU maintenance purposes * CPU doesn't need to maintain the tick for RCU maintenance purposes
* when the CPU runs in userspace. * 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) void rcu_user_enter(void)
{ {
@ -875,6 +881,9 @@ void rcu_user_enter(void)
* Use things like work queues to work around this limitation. * Use things like work queues to work around this limitation.
* *
* You have been warned. * 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) void rcu_irq_exit(void)
{ {
@ -899,6 +908,9 @@ void rcu_irq_exit(void)
/* /*
* Wrapper for rcu_irq_exit() where interrupts are enabled. * 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) 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 * allow for the possibility of usermode upcalls messing up our count
* of interrupt nesting level during the busy period that is just * of interrupt nesting level during the busy period that is just
* now starting. * 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) 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 * Exit RCU idle mode while entering the kernel because it can
* run a RCU read side critical section anytime. * 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) void rcu_user_exit(void)
{ {
@ -1012,6 +1030,9 @@ void rcu_user_exit(void)
* Use things like work queues to work around this limitation. * Use things like work queues to work around this limitation.
* *
* You have been warned. * 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) void rcu_irq_enter(void)
{ {
@ -1037,6 +1058,9 @@ void rcu_irq_enter(void)
/* /*
* Wrapper for rcu_irq_enter() where interrupts are enabled. * 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) 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 * that the CPU is active. This implementation permits nested NMIs, as
* long as the nesting level does not overflow an int. (You will probably * long as the nesting level does not overflow an int. (You will probably
* run out of stack space first.) * 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) 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 * 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 * to let the RCU grace-period handling know that the CPU is back to
* being RCU-idle. * 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) void rcu_nmi_exit(void)
{ {