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rcu: Enable DEBUG_OBJECTS_RCU_HEAD from !PREEMPT 

The prohibition of DEBUG_OBJECTS_RCU_HEAD from !PREEMPT was due to the
fixup actions.  So just produce a warning from !PREEMPT.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
This commit is contained in:
Mathieu Desnoyers 2011-02-23 09:42:14 -08:00 committed by Paul E. McKenney
parent 5ece5bab3e
commit fc2ecf7ec7
2 changed files with 22 additions and 6 deletions
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26
kernel/rcupdate.c
View File

@ -142,7 +142,14 @@ static int rcuhead_fixup_init(void *addr, enum debug_obj_state state)
* Ensure that queued callbacks are all executed.
* If we detect that we are nested in a RCU read-side critical
* section, we should simply fail, otherwise we would deadlock.
* In !PREEMPT configurations, there is no way to tell if we are
* in a RCU read-side critical section or not, so we never
* attempt any fixup and just print a warning.
*/
#ifndef CONFIG_PREEMPT
WARN_ON(1);
return 0;
#endif
if (rcu_preempt_depth() != 0 || preempt_count() != 0 ||
irqs_disabled()) {
WARN_ON(1);
@ -184,7 +191,14 @@ static int rcuhead_fixup_activate(void *addr, enum debug_obj_state state)
* Ensure that queued callbacks are all executed.
* If we detect that we are nested in a RCU read-side critical
* section, we should simply fail, otherwise we would deadlock.
* In !PREEMPT configurations, there is no way to tell if we are
* in a RCU read-side critical section or not, so we never
* attempt any fixup and just print a warning.
*/
#ifndef CONFIG_PREEMPT
WARN_ON(1);
return 0;
#endif
if (rcu_preempt_depth() != 0 || preempt_count() != 0 ||
irqs_disabled()) {
WARN_ON(1);
@ -214,12 +228,14 @@ static int rcuhead_fixup_free(void *addr, enum debug_obj_state state)
* Ensure that queued callbacks are all executed.
* If we detect that we are nested in a RCU read-side critical
* section, we should simply fail, otherwise we would deadlock.
* Note that the machinery to reliably determine whether
* or not we are in an RCU read-side critical section
* exists only in the preemptible RCU implementations
* (TINY_PREEMPT_RCU and TREE_PREEMPT_RCU), which is why
* DEBUG_OBJECTS_RCU_HEAD is disallowed if !PREEMPT.
* In !PREEMPT configurations, there is no way to tell if we are
* in a RCU read-side critical section or not, so we never
* attempt any fixup and just print a warning.
*/
#ifndef CONFIG_PREEMPT
WARN_ON(1);
return 0;
#endif
if (rcu_preempt_depth() != 0 || preempt_count() != 0 ||
irqs_disabled()) {
WARN_ON(1);

2
lib/Kconfig.debug
View File

@ -337,7 +337,7 @@ config DEBUG_OBJECTS_WORK
config DEBUG_OBJECTS_RCU_HEAD
bool "Debug RCU callbacks objects"
depends on DEBUG_OBJECTS && PREEMPT
depends on DEBUG_OBJECTS
help
Enable this to turn on debugging of RCU list heads (call_rcu() usage).