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Commit fc2ecf7e authored by Mathieu Desnoyers's avatar Mathieu Desnoyers Committed by Paul E. McKenney
Browse files

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: default avatarMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: default avatarJosh Triplett <josh@joshtriplett.org>
parent 5ece5bab

kernel/rcupdate.c

+21 −5
Original line number Diff line number Diff line
@@ -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);

lib/Kconfig.debug

+1 −1
Original line number Diff line number Diff line
@@ -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).