Commit c0da313e authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

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: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 02a7c234

kernel/rcu/tree.c

+30 −0
Original line number Diff line number Diff line
@@ -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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